APE Price: $1.25 (+3.51%)
    /

    Contract Diff Checker

    Contract Name:
    CamelotPair

    Contract Source Code:

    pragma solidity =0.5.16;
    
    import './interfaces/ICamelotPair.sol';
    import './UniswapV2ERC20.sol';
    import './libraries/Math.sol';
    import './interfaces/IERC20.sol';
    import './interfaces/ICamelotFactory.sol';
    import './interfaces/IUniswapV2Callee.sol';
    
    contract CamelotPair is ICamelotPair, UniswapV2ERC20 {
      using SafeMath  for uint;
    
      uint public constant MINIMUM_LIQUIDITY = 10 ** 3;
      bytes4 private constant SELECTOR = bytes4(keccak256(bytes('transfer(address,uint256)')));
    
      address public factory;
      address public token0;
      address public token1;
    
      bool public initialized;
    
      uint public constant FEE_DENOMINATOR = 100000;
      uint public constant MAX_FEE_PERCENT = 2000; // = 2%
    
      uint112 private reserve0;           // uses single storage slot, accessible via getReserves
      uint112 private reserve1;           // uses single storage slot, accessible via getReserves
      uint16 public token0FeePercent = 500; // default = 0.5%  // uses single storage slot, accessible via getReserves
      uint16 public token1FeePercent = 500; // default = 0.5%  // uses single storage slot, accessible via getReserves
    
      uint public precisionMultiplier0;
      uint public precisionMultiplier1;
    
      uint public kLast; // reserve0 * reserve1, as of immediately after the most recent liquidity event
    
      bool public stableSwap; // if set to true, defines pair type as stable
      bool public pairTypeImmutable; // if set to true, stableSwap states cannot be updated anymore
    
      uint private unlocked = 1;
      modifier lock() {
        require(unlocked == 1, 'CamelotPair: LOCKED');
        unlocked = 0;
        _;
        unlocked = 1;
      }
    
      function getReserves() public view returns (uint112 _reserve0, uint112 _reserve1, uint16 _token0FeePercent, uint16 _token1FeePercent) {
        _reserve0 = reserve0;
        _reserve1 = reserve1;
        _token0FeePercent = token0FeePercent;
        _token1FeePercent = token1FeePercent;
      }
    
      function _safeTransfer(address token, address to, uint value) private {
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'CamelotPair: TRANSFER_FAILED');
      }
    
      event DrainWrongToken(address indexed token, address to);
      event FeePercentUpdated(uint16 token0FeePercent, uint16 token1FeePercent);
      event SetStableSwap(bool prevStableSwap, bool stableSwap);
      event SetPairTypeImmutable();
      event Mint(address indexed sender, uint amount0, uint amount1);
      event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
      event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
      );
      event Sync(uint112 reserve0, uint112 reserve1);
      event Skim();
    
      constructor() public {
        factory = msg.sender;
      }
    
      // called once by the factory at time of deployment
      function initialize(address _token0, address _token1) external {
        require(msg.sender == factory && !initialized, 'CamelotPair: FORBIDDEN');
        // sufficient check
        token0 = _token0;
        token1 = _token1;
    
        precisionMultiplier0 = 10 ** uint(IERC20(_token0).decimals());
        precisionMultiplier1 = 10 ** uint(IERC20(_token1).decimals());
    
        initialized = true;
      }
    
      /**
      * @dev Updates the swap fees percent
      *
      * Can only be called by the factory's feeAmountOwner
      */
      function setFeePercent(uint16 newToken0FeePercent, uint16 newToken1FeePercent) external lock {
        require(msg.sender == ICamelotFactory(factory).feePercentOwner(), "CamelotPair: only factory's feeAmountOwner");
        require(newToken0FeePercent <= MAX_FEE_PERCENT && newToken1FeePercent <= MAX_FEE_PERCENT, "CamelotPair: feePercent mustn't exceed the maximum");
        require(newToken0FeePercent > 0 && newToken1FeePercent > 0, "CamelotPair: feePercent mustn't exceed the minimum");
        token0FeePercent = newToken0FeePercent;
        token1FeePercent = newToken1FeePercent;
        emit FeePercentUpdated(newToken0FeePercent, newToken1FeePercent);
      }
    
      function setStableSwap(bool stable, uint112 expectedReserve0, uint112 expectedReserve1) external lock {
        require(msg.sender == ICamelotFactory(factory).setStableOwner(), "CamelotPair: only factory's setStableOwner");
        require(!pairTypeImmutable, "CamelotPair: immutable");
    
        require(stable != stableSwap, "CamelotPair: no update");
        require(expectedReserve0 == reserve0 && expectedReserve1 == reserve1, "CamelotPair: failed");
    
        bool feeOn = _mintFee(reserve0, reserve1);
    
        emit SetStableSwap(stableSwap, stable);
        stableSwap = stable;
        kLast = (stable && feeOn) ? _k(uint(reserve0), uint(reserve1)) : 0;
      }
    
      function setPairTypeImmutable() external lock {
        require(msg.sender == ICamelotFactory(factory).owner(), "CamelotPair: only factory's owner");
        require(!pairTypeImmutable, "CamelotPair: already immutable");
    
        pairTypeImmutable = true;
        emit SetPairTypeImmutable();
      }
    
      // update reserves
      function _update(uint balance0, uint balance1) private {
        require(balance0 <= uint112(- 1) && balance1 <= uint112(- 1), 'CamelotPair: OVERFLOW');
    
        reserve0 = uint112(balance0);
        reserve1 = uint112(balance1);
        emit Sync(uint112(balance0), uint112(balance1));
      }
    
      // if fee is on, mint liquidity equivalent to "factory.ownerFeeShare()" of the growth in sqrt(k)
      // only for uni configuration
      function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
        if(stableSwap) return false;
    
        (uint ownerFeeShare, address feeTo) = ICamelotFactory(factory).feeInfo();
        feeOn = feeTo != address(0);
        uint _kLast = kLast;
        // gas savings
        if (feeOn) {
          if (_kLast != 0) {
            uint rootK = Math.sqrt(_k(uint(_reserve0), uint(_reserve1)));
            uint rootKLast = Math.sqrt(_kLast);
            if (rootK > rootKLast) {
              uint d = (FEE_DENOMINATOR.mul(100) / ownerFeeShare).sub(100);
              uint numerator = totalSupply.mul(rootK.sub(rootKLast)).mul(100);
              uint denominator = rootK.mul(d).add(rootKLast.mul(100));
              uint liquidity = numerator / denominator;
              if (liquidity > 0) _mint(feeTo, liquidity);
            }
          }
        } else if (_kLast != 0) {
          kLast = 0;
        }
      }
    
      // this low-level function should be called from a contract which performs important safety checks
      function mint(address to) external lock returns (uint liquidity) {
        (uint112 _reserve0, uint112 _reserve1,,) = getReserves();
        // gas savings
        uint balance0 = IERC20(token0).balanceOf(address(this));
        uint balance1 = IERC20(token1).balanceOf(address(this));
        uint amount0 = balance0.sub(_reserve0);
        uint amount1 = balance1.sub(_reserve1);
    
        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply;
        // gas savings, must be defined here since totalSupply can update in _mintFee
        if (_totalSupply == 0) {
          liquidity = Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
          _mint(address(0), MINIMUM_LIQUIDITY);
          // permanently lock the first MINIMUM_LIQUIDITY tokens
        } else {
          liquidity = Math.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
        }
        require(liquidity > 0, 'CamelotPair: INSUFFICIENT_LIQUIDITY_MINTED');
        _mint(to, liquidity);
    
        _update(balance0, balance1);
        if (feeOn) kLast = _k(uint(reserve0), uint(reserve1));
        // reserve0 and reserve1 are up-to-date
        emit Mint(msg.sender, amount0, amount1);
      }
    
      // this low-level function should be called from a contract which performs important safety checks
      function burn(address to) external lock returns (uint amount0, uint amount1) {
        (uint112 _reserve0, uint112 _reserve1,,) = getReserves(); // gas savings
        address _token0 = token0; // gas savings
        address _token1 = token1; // gas savings
        uint balance0 = IERC20(_token0).balanceOf(address(this));
        uint balance1 = IERC20(_token1).balanceOf(address(this));
        uint liquidity = balanceOf[address(this)];
    
        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        amount0 = liquidity.mul(balance0) / _totalSupply; // using balances ensures pro-rata distribution
        amount1 = liquidity.mul(balance1) / _totalSupply; // using balances ensures pro-rata distribution
        require(amount0 > 0 && amount1 > 0, 'CamelotPair: INSUFFICIENT_LIQUIDITY_BURNED');
        _burn(address(this), liquidity);
        _safeTransfer(_token0, to, amount0);
        _safeTransfer(_token1, to, amount1);
        balance0 = IERC20(_token0).balanceOf(address(this));
        balance1 = IERC20(_token1).balanceOf(address(this));
    
        _update(balance0, balance1);
        if (feeOn) kLast = _k(uint(reserve0), uint(reserve1)); // reserve0 and reserve1 are up-to-date
        emit Burn(msg.sender, amount0, amount1, to);
      }
    
      struct TokensData {
        address token0;
        address token1;
        uint amount0Out;
        uint amount1Out;
        uint balance0;
        uint balance1;
        uint remainingFee0;
        uint remainingFee1;
      }
    
      // this low-level function should be called from a contract which performs important safety checks
      function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external {
        TokensData memory tokensData = TokensData({
          token0: token0,
          token1: token1,
          amount0Out: amount0Out,
          amount1Out: amount1Out,
          balance0: 0,
          balance1: 0,
          remainingFee0: 0,
          remainingFee1: 0
        });
        _swap(tokensData, to, data, address(0));
      }
    
      // this low-level function should be called from a contract which performs important safety checks
      function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data, address referrer) external {
        TokensData memory tokensData = TokensData({
          token0: token0,
          token1: token1,
          amount0Out: amount0Out,
          amount1Out: amount1Out,
          balance0: 0,
          balance1: 0,
          remainingFee0: 0,
          remainingFee1: 0
        });
        _swap(tokensData, to, data, referrer);
      }
    
    
      function _swap(TokensData memory tokensData, address to, bytes memory data, address referrer) internal lock {
        require(tokensData.amount0Out > 0 || tokensData.amount1Out > 0, 'CamelotPair: INSUFFICIENT_OUTPUT_AMOUNT');
    
        (uint112 _reserve0, uint112 _reserve1, uint16 _token0FeePercent, uint16 _token1FeePercent) = getReserves();
        require(tokensData.amount0Out < _reserve0 && tokensData.amount1Out < _reserve1, 'CamelotPair: INSUFFICIENT_LIQUIDITY');
    
    
        {
          require(to != tokensData.token0 && to != tokensData.token1, 'CamelotPair: INVALID_TO');
          // optimistically transfer tokens
          if (tokensData.amount0Out > 0) _safeTransfer(tokensData.token0, to, tokensData.amount0Out);
          // optimistically transfer tokens
          if (tokensData.amount1Out > 0) _safeTransfer(tokensData.token1, to, tokensData.amount1Out);
          if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(msg.sender, tokensData.amount0Out, tokensData.amount1Out, data);
          tokensData.balance0 = IERC20(tokensData.token0).balanceOf(address(this));
          tokensData.balance1 = IERC20(tokensData.token1).balanceOf(address(this));
        }
    
        uint amount0In = tokensData.balance0 > _reserve0 - tokensData.amount0Out ? tokensData.balance0 - (_reserve0 - tokensData.amount0Out) : 0;
        uint amount1In = tokensData.balance1 > _reserve1 - tokensData.amount1Out ? tokensData.balance1 - (_reserve1 - tokensData.amount1Out) : 0;
        require(amount0In > 0 || amount1In > 0, 'CamelotPair: INSUFFICIENT_INPUT_AMOUNT');
    
        tokensData.remainingFee0 = amount0In.mul(_token0FeePercent) / FEE_DENOMINATOR;
        tokensData.remainingFee1 = amount1In.mul(_token1FeePercent) / FEE_DENOMINATOR;
    
        {// scope for referer/stable fees management
          uint fee = 0;
    
          uint referrerInputFeeShare = referrer != address(0) ? ICamelotFactory(factory).referrersFeeShare(referrer) : 0;
          if (referrerInputFeeShare > 0) {
            if (amount0In > 0) {
              fee = amount0In.mul(referrerInputFeeShare).mul(_token0FeePercent) / (FEE_DENOMINATOR ** 2);
              tokensData.remainingFee0 = tokensData.remainingFee0.sub(fee);
              _safeTransfer(tokensData.token0, referrer, fee);
            }
            if (amount1In > 0) {
              fee = amount1In.mul(referrerInputFeeShare).mul(_token1FeePercent) / (FEE_DENOMINATOR ** 2);
              tokensData.remainingFee1 = tokensData.remainingFee1.sub(fee);
              _safeTransfer(tokensData.token1, referrer, fee);
            }
          }
    
          if(stableSwap){
            (uint ownerFeeShare, address feeTo) = ICamelotFactory(factory).feeInfo();
            if(feeTo != address(0)) {
              ownerFeeShare = FEE_DENOMINATOR.sub(referrerInputFeeShare).mul(ownerFeeShare);
              if (amount0In > 0) {
                fee = amount0In.mul(ownerFeeShare).mul(_token0FeePercent) / (FEE_DENOMINATOR ** 3);
                tokensData.remainingFee0 = tokensData.remainingFee0.sub(fee);
                _safeTransfer(tokensData.token0, feeTo, fee);
              }
              if (amount1In > 0) {
                fee = amount1In.mul(ownerFeeShare).mul(_token1FeePercent) / (FEE_DENOMINATOR ** 3);
                tokensData.remainingFee1 = tokensData.remainingFee1.sub(fee);
                _safeTransfer(tokensData.token1, feeTo, fee);
              }
            }
          }
          // readjust tokens balance
          if (amount0In > 0) tokensData.balance0 = IERC20(tokensData.token0).balanceOf(address(this));
          if (amount1In > 0) tokensData.balance1 = IERC20(tokensData.token1).balanceOf(address(this));
        }
        {// scope for reserve{0,1}Adjusted, avoids stack too deep errors
          uint balance0Adjusted = tokensData.balance0.sub(tokensData.remainingFee0);
          uint balance1Adjusted = tokensData.balance1.sub(tokensData.remainingFee1);
          require(_k(balance0Adjusted, balance1Adjusted) >= _k(uint(_reserve0), uint(_reserve1)), 'CamelotPair: K');
        }
        _update(tokensData.balance0, tokensData.balance1);
        emit Swap(msg.sender, amount0In, amount1In, tokensData.amount0Out, tokensData.amount1Out, to);
      }
    
      function _k(uint balance0, uint balance1) internal view returns (uint) {
        if (stableSwap) {
          uint _x = balance0.mul(1e18) / precisionMultiplier0;
          uint _y = balance1.mul(1e18) / precisionMultiplier1;
          uint _a = (_x.mul(_y)) / 1e18;
          uint _b = (_x.mul(_x) / 1e18).add(_y.mul(_y) / 1e18);
          return  _a.mul(_b) / 1e18; // x3y+y3x >= k
        }
        return balance0.mul(balance1);
      }
    
      function _get_y(uint x0, uint xy, uint y) internal pure returns (uint) {
        for (uint i = 0; i < 255; i++) {
          uint y_prev = y;
          uint k = _f(x0, y);
          if (k < xy) {
            uint dy = (xy - k) * 1e18 / _d(x0, y);
            y = y + dy;
          } else {
            uint dy = (k - xy) * 1e18 / _d(x0, y);
            y = y - dy;
          }
          if (y > y_prev) {
            if (y - y_prev <= 1) {
              return y;
            }
          } else {
            if (y_prev - y <= 1) {
              return y;
            }
          }
        }
        return y;
      }
    
      function _f(uint x0, uint y) internal pure returns (uint) {
        return x0 * (y * y / 1e18 * y / 1e18) / 1e18 + (x0 * x0 / 1e18 * x0 / 1e18) * y / 1e18;
      }
    
      function _d(uint x0, uint y) internal pure returns (uint) {
        return 3 * x0 * (y * y / 1e18) / 1e18 + (x0 * x0 / 1e18 * x0 / 1e18);
      }
    
      function getAmountOut(uint amountIn, address tokenIn) external view returns (uint) {
        uint16 feePercent = tokenIn == token0 ? token0FeePercent : token1FeePercent;
        return _getAmountOut(amountIn, tokenIn, uint(reserve0), uint(reserve1), feePercent);
      }
    
      function _getAmountOut(uint amountIn, address tokenIn, uint _reserve0, uint _reserve1, uint feePercent) internal view returns (uint) {
        if (stableSwap) {
          amountIn = amountIn.sub(amountIn.mul(feePercent) / FEE_DENOMINATOR); // remove fee from amount received
          uint xy = _k(_reserve0, _reserve1);
          _reserve0 = _reserve0 * 1e18 / precisionMultiplier0;
          _reserve1 = _reserve1 * 1e18 / precisionMultiplier1;
    
          (uint reserveA, uint reserveB) = tokenIn == token0 ? (_reserve0, _reserve1) : (_reserve1, _reserve0);
          amountIn = tokenIn == token0 ? amountIn * 1e18 / precisionMultiplier0 : amountIn * 1e18 / precisionMultiplier1;
          uint y = reserveB - _get_y(amountIn + reserveA, xy, reserveB);
          return y * (tokenIn == token0 ? precisionMultiplier1 : precisionMultiplier0) / 1e18;
    
        } else {
          (uint reserveA, uint reserveB) = tokenIn == token0 ? (_reserve0, _reserve1) : (_reserve1, _reserve0);
          amountIn = amountIn.mul(FEE_DENOMINATOR.sub(feePercent));
          return (amountIn.mul(reserveB)) / (reserveA.mul(FEE_DENOMINATOR).add(amountIn));
        }
      }
    
      // force balances to match reserves
      function skim(address to) external lock {
        address _token0 = token0;
        // gas savings
        address _token1 = token1;
        // gas savings
        _safeTransfer(_token0, to, IERC20(_token0).balanceOf(address(this)).sub(reserve0));
        _safeTransfer(_token1, to, IERC20(_token1).balanceOf(address(this)).sub(reserve1));
        emit Skim();
      }
    
      // force reserves to match balances
      function sync() external lock {
        uint token0Balance = IERC20(token0).balanceOf(address(this));
        uint token1Balance = IERC20(token1).balanceOf(address(this));
        require(token0Balance != 0 && token1Balance != 0, "CamelotPair: liquidity ratio not initialized");
        _update(token0Balance, token1Balance);
      }
    
      /**
      * @dev Allow to recover token sent here by mistake
      *
      * Can only be called by factory's owner
      */
      function drainWrongToken(address token, address to) external lock {
        require(msg.sender == ICamelotFactory(factory).owner(), "CamelotPair: only factory's owner");
        require(token != token0 && token != token1, "CamelotPair: invalid token");
        _safeTransfer(token, to, IERC20(token).balanceOf(address(this)));
        emit DrainWrongToken(token, to);
      }
    }

    pragma solidity >=0.5.0;
    
    interface ICamelotFactory {
        event PairCreated(address indexed token0, address indexed token1, address pair, uint256);
    
        function owner() external view returns (address);
        function feePercentOwner() external view returns (address);
        function setStableOwner() external view returns (address);
        function feeTo() external view returns (address);
    
        function ownerFeeShare() external view returns (uint256);
        function referrersFeeShare(address) external view returns (uint256);
    
        function getPair(address tokenA, address tokenB) external view returns (address pair);
        function allPairs(uint256) external view returns (address pair);
        function allPairsLength() external view returns (uint256);
    
        function createPair(address tokenA, address tokenB) external returns (address pair);
    
        function setFeeTo(address) external;
        function feeInfo() external view returns (uint _ownerFeeShare, address _feeTo);
    }

    pragma solidity >=0.5.0;
    
    interface ICamelotPair {
        event Approval(address indexed owner, address indexed spender, uint value);
        event Transfer(address indexed from, address indexed to, uint value);
    
        function name() external pure returns (string memory);
        function symbol() external pure returns (string memory);
        function decimals() external pure returns (uint8);
        function totalSupply() external view returns (uint);
        function balanceOf(address owner) external view returns (uint);
        function allowance(address owner, address spender) external view returns (uint);
    
        function approve(address spender, uint value) external returns (bool);
        function transfer(address to, uint value) external returns (bool);
        function transferFrom(address from, address to, uint value) external returns (bool);
    
        function DOMAIN_SEPARATOR() external view returns (bytes32);
        function PERMIT_TYPEHASH() external pure returns (bytes32);
        function nonces(address owner) external view returns (uint);
    
        function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
    
        event Mint(address indexed sender, uint amount0, uint amount1);
        event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
        event Swap(
            address indexed sender,
            uint amount0In,
            uint amount1In,
            uint amount0Out,
            uint amount1Out,
            address indexed to
        );
        event Sync(uint112 reserve0, uint112 reserve1);
    
        function MINIMUM_LIQUIDITY() external pure returns (uint);
        function factory() external view returns (address);
        function token0() external view returns (address);
        function token1() external view returns (address);
        function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint16 token0feePercent, uint16 token1FeePercent);
        function getAmountOut(uint amountIn, address tokenIn) external view returns (uint);
        function kLast() external view returns (uint);
    
        function setFeePercent(uint16 token0FeePercent, uint16 token1FeePercent) external;
        function mint(address to) external returns (uint liquidity);
        function burn(address to) external returns (uint amount0, uint amount1);
        function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
        function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data, address referrer) external;
        function skim(address to) external;
        function sync() external;
    
        function initialize(address, address) external;
    }

    pragma solidity >=0.5.0;
    
    interface IERC20 {
        event Approval(address indexed owner, address indexed spender, uint value);
        event Transfer(address indexed from, address indexed to, uint value);
    
        function name() external view returns (string memory);
        function symbol() external view returns (string memory);
        function decimals() external view returns (uint8);
        function totalSupply() external view returns (uint);
        function balanceOf(address owner) external view returns (uint);
        function allowance(address owner, address spender) external view returns (uint);
    
        function approve(address spender, uint value) external returns (bool);
        function transfer(address to, uint value) external returns (bool);
        function transferFrom(address from, address to, uint value) external returns (bool);
    }

    pragma solidity >=0.5.0;
    
    interface IUniswapV2Callee {
        function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
    }

    pragma solidity >=0.5.0;
    
    interface IUniswapV2ERC20 {
        event Approval(address indexed owner, address indexed spender, uint value);
        event Transfer(address indexed from, address indexed to, uint value);
    
        function name() external pure returns (string memory);
        function symbol() external pure returns (string memory);
        function decimals() external pure returns (uint8);
        function totalSupply() external view returns (uint);
        function balanceOf(address owner) external view returns (uint);
        function allowance(address owner, address spender) external view returns (uint);
    
        function approve(address spender, uint value) external returns (bool);
        function transfer(address to, uint value) external returns (bool);
        function transferFrom(address from, address to, uint value) external returns (bool);
    
        function DOMAIN_SEPARATOR() external view returns (bytes32);
        function PERMIT_TYPEHASH() external pure returns (bytes32);
        function nonces(address owner) external view returns (uint);
    
        function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
    }

    pragma solidity =0.5.16;
    
    // a library for performing various math operations
    
    library Math {
        function min(uint x, uint y) internal pure returns (uint z) {
            z = x < y ? x : y;
        }
    
        // babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
        function sqrt(uint y) internal pure returns (uint z) {
            if (y > 3) {
                z = y;
                uint x = y / 2 + 1;
                while (x < z) {
                    z = x;
                    x = (y / x + x) / 2;
                }
            } else if (y != 0) {
                z = 1;
            }
        }
    }

    pragma solidity =0.5.16;
    
    // a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)
    
    library SafeMath {
        function add(uint x, uint y) internal pure returns (uint z) {
            require((z = x + y) >= x, 'ds-math-add-overflow');
        }
    
        function sub(uint x, uint y) internal pure returns (uint z) {
            require((z = x - y) <= x, 'ds-math-sub-underflow');
        }
    
        function mul(uint x, uint y) internal pure returns (uint z) {
            require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
        }
    }

    pragma solidity =0.5.16;
    
    import './interfaces/IUniswapV2ERC20.sol';
    import './libraries/SafeMath.sol';
    
    contract UniswapV2ERC20 is IUniswapV2ERC20 {
        using SafeMath for uint;
    
        string public constant name = 'Camelot LP';
        string public constant symbol = 'CMLT-LP';
        uint8 public constant decimals = 18;
        uint  public totalSupply;
        mapping(address => uint) public balanceOf;
        mapping(address => mapping(address => uint)) public allowance;
    
        bytes32 public DOMAIN_SEPARATOR;
        // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
        bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
        mapping(address => uint) public nonces;
    
        event Approval(address indexed owner, address indexed spender, uint value);
        event Transfer(address indexed from, address indexed to, uint value);
    
        constructor() public {
            uint chainId;
            assembly {
                chainId := chainid
            }
            DOMAIN_SEPARATOR = keccak256(
                abi.encode(
                    keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                    keccak256(bytes(name)),
                    keccak256(bytes('1')),
                    chainId,
                    address(this)
                )
            );
        }
    
        function _mint(address to, uint value) internal {
            totalSupply = totalSupply.add(value);
            balanceOf[to] = balanceOf[to].add(value);
            emit Transfer(address(0), to, value);
        }
    
        function _burn(address from, uint value) internal {
            balanceOf[from] = balanceOf[from].sub(value);
            totalSupply = totalSupply.sub(value);
            emit Transfer(from, address(0), value);
        }
    
        function _approve(address owner, address spender, uint value) private {
            allowance[owner][spender] = value;
            emit Approval(owner, spender, value);
        }
    
        function _transfer(address from, address to, uint value) private {
            balanceOf[from] = balanceOf[from].sub(value);
            balanceOf[to] = balanceOf[to].add(value);
            emit Transfer(from, to, value);
        }
    
        function approve(address spender, uint value) external returns (bool) {
            _approve(msg.sender, spender, value);
            return true;
        }
    
        function transfer(address to, uint value) external returns (bool) {
            _transfer(msg.sender, to, value);
            return true;
        }
    
        function transferFrom(address from, address to, uint value) external returns (bool) {
            if (allowance[from][msg.sender] != uint(-1)) {
                uint remaining = allowance[from][msg.sender].sub(value);
                allowance[from][msg.sender] = remaining;
                emit Approval(from, msg.sender, remaining);
            }
            _transfer(from, to, value);
            return true;
        }
    
        function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
            require(deadline >= block.timestamp, 'UniswapV2: EXPIRED');
            bytes32 digest = keccak256(
                abi.encodePacked(
                    '\x19\x01',
                    DOMAIN_SEPARATOR,
                    keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
                )
            );
            address recoveredAddress = ecrecover(digest, v, r, s);
            require(recoveredAddress != address(0) && recoveredAddress == owner, 'UniswapV2: INVALID_SIGNATURE');
            _approve(owner, spender, value);
        }
    }

    Contract Name:
    CamelotPair

    Contract Source Code:

    pragma solidity =0.5.16;
    
    import './interfaces/ICamelotPair.sol';
    import './UniswapV2ERC20.sol';
    import './libraries/Math.sol';
    import './interfaces/IERC20.sol';
    import './interfaces/ICamelotFactory.sol';
    import './interfaces/IUniswapV2Callee.sol';
    
    contract CamelotPair is ICamelotPair, UniswapV2ERC20 {
      using SafeMath  for uint;
    
      uint public constant MINIMUM_LIQUIDITY = 10 ** 3;
      bytes4 private constant SELECTOR = bytes4(keccak256(bytes('transfer(address,uint256)')));
    
      address public factory;
      address public token0;
      address public token1;
    
      bool public initialized;
    
      uint public constant FEE_DENOMINATOR = 100000;
      uint public constant MAX_FEE_PERCENT = 2000; // = 2%
    
      uint112 private reserve0;           // uses single storage slot, accessible via getReserves
      uint112 private reserve1;           // uses single storage slot, accessible via getReserves
      uint16 public token0FeePercent = 500; // default = 0.5%  // uses single storage slot, accessible via getReserves
      uint16 public token1FeePercent = 500; // default = 0.5%  // uses single storage slot, accessible via getReserves
    
      uint public precisionMultiplier0;
      uint public precisionMultiplier1;
    
      uint public kLast; // reserve0 * reserve1, as of immediately after the most recent liquidity event
    
      bool public stableSwap; // if set to true, defines pair type as stable
      bool public pairTypeImmutable; // if set to true, stableSwap states cannot be updated anymore
    
      uint private unlocked = 1;
      modifier lock() {
        require(unlocked == 1, 'CamelotPair: LOCKED');
        unlocked = 0;
        _;
        unlocked = 1;
      }
    
      function getReserves() public view returns (uint112 _reserve0, uint112 _reserve1, uint16 _token0FeePercent, uint16 _token1FeePercent) {
        _reserve0 = reserve0;
        _reserve1 = reserve1;
        _token0FeePercent = token0FeePercent;
        _token1FeePercent = token1FeePercent;
      }
    
      function _safeTransfer(address token, address to, uint value) private {
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'CamelotPair: TRANSFER_FAILED');
      }
    
      event DrainWrongToken(address indexed token, address to);
      event FeePercentUpdated(uint16 token0FeePercent, uint16 token1FeePercent);
      event SetStableSwap(bool prevStableSwap, bool stableSwap);
      event SetPairTypeImmutable();
      event Mint(address indexed sender, uint amount0, uint amount1);
      event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
      event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
      );
      event Sync(uint112 reserve0, uint112 reserve1);
      event Skim();
    
      constructor() public {
        factory = msg.sender;
      }
    
      // called once by the factory at time of deployment
      function initialize(address _token0, address _token1) external {
        require(msg.sender == factory && !initialized, 'CamelotPair: FORBIDDEN');
        // sufficient check
        token0 = _token0;
        token1 = _token1;
    
        precisionMultiplier0 = 10 ** uint(IERC20(_token0).decimals());
        precisionMultiplier1 = 10 ** uint(IERC20(_token1).decimals());
    
        initialized = true;
      }
    
      /**
      * @dev Updates the swap fees percent
      *
      * Can only be called by the factory's feeAmountOwner
      */
      function setFeePercent(uint16 newToken0FeePercent, uint16 newToken1FeePercent) external lock {
        require(msg.sender == ICamelotFactory(factory).feePercentOwner(), "CamelotPair: only factory's feeAmountOwner");
        require(newToken0FeePercent <= MAX_FEE_PERCENT && newToken1FeePercent <= MAX_FEE_PERCENT, "CamelotPair: feePercent mustn't exceed the maximum");
        require(newToken0FeePercent > 0 && newToken1FeePercent > 0, "CamelotPair: feePercent mustn't exceed the minimum");
        token0FeePercent = newToken0FeePercent;
        token1FeePercent = newToken1FeePercent;
        emit FeePercentUpdated(newToken0FeePercent, newToken1FeePercent);
      }
    
      function setStableSwap(bool stable, uint112 expectedReserve0, uint112 expectedReserve1) external lock {
        require(msg.sender == ICamelotFactory(factory).setStableOwner(), "CamelotPair: only factory's setStableOwner");
        require(!pairTypeImmutable, "CamelotPair: immutable");
    
        require(stable != stableSwap, "CamelotPair: no update");
        require(expectedReserve0 == reserve0 && expectedReserve1 == reserve1, "CamelotPair: failed");
    
        bool feeOn = _mintFee(reserve0, reserve1);
    
        emit SetStableSwap(stableSwap, stable);
        stableSwap = stable;
        kLast = (stable && feeOn) ? _k(uint(reserve0), uint(reserve1)) : 0;
      }
    
      function setPairTypeImmutable() external lock {
        require(msg.sender == ICamelotFactory(factory).owner(), "CamelotPair: only factory's owner");
        require(!pairTypeImmutable, "CamelotPair: already immutable");
    
        pairTypeImmutable = true;
        emit SetPairTypeImmutable();
      }
    
      // update reserves
      function _update(uint balance0, uint balance1) private {
        require(balance0 <= uint112(- 1) && balance1 <= uint112(- 1), 'CamelotPair: OVERFLOW');
    
        reserve0 = uint112(balance0);
        reserve1 = uint112(balance1);
        emit Sync(uint112(balance0), uint112(balance1));
      }
    
      // if fee is on, mint liquidity equivalent to "factory.ownerFeeShare()" of the growth in sqrt(k)
      // only for uni configuration
      function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
        if(stableSwap) return false;
    
        (uint ownerFeeShare, address feeTo) = ICamelotFactory(factory).feeInfo();
        feeOn = feeTo != address(0);
        uint _kLast = kLast;
        // gas savings
        if (feeOn) {
          if (_kLast != 0) {
            uint rootK = Math.sqrt(_k(uint(_reserve0), uint(_reserve1)));
            uint rootKLast = Math.sqrt(_kLast);
            if (rootK > rootKLast) {
              uint d = (FEE_DENOMINATOR.mul(100) / ownerFeeShare).sub(100);
              uint numerator = totalSupply.mul(rootK.sub(rootKLast)).mul(100);
              uint denominator = rootK.mul(d).add(rootKLast.mul(100));
              uint liquidity = numerator / denominator;
              if (liquidity > 0) _mint(feeTo, liquidity);
            }
          }
        } else if (_kLast != 0) {
          kLast = 0;
        }
      }
    
      // this low-level function should be called from a contract which performs important safety checks
      function mint(address to) external lock returns (uint liquidity) {
        (uint112 _reserve0, uint112 _reserve1,,) = getReserves();
        // gas savings
        uint balance0 = IERC20(token0).balanceOf(address(this));
        uint balance1 = IERC20(token1).balanceOf(address(this));
        uint amount0 = balance0.sub(_reserve0);
        uint amount1 = balance1.sub(_reserve1);
    
        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply;
        // gas savings, must be defined here since totalSupply can update in _mintFee
        if (_totalSupply == 0) {
          liquidity = Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
          _mint(address(0), MINIMUM_LIQUIDITY);
          // permanently lock the first MINIMUM_LIQUIDITY tokens
        } else {
          liquidity = Math.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
        }
        require(liquidity > 0, 'CamelotPair: INSUFFICIENT_LIQUIDITY_MINTED');
        _mint(to, liquidity);
    
        _update(balance0, balance1);
        if (feeOn) kLast = _k(uint(reserve0), uint(reserve1));
        // reserve0 and reserve1 are up-to-date
        emit Mint(msg.sender, amount0, amount1);
      }
    
      // this low-level function should be called from a contract which performs important safety checks
      function burn(address to) external lock returns (uint amount0, uint amount1) {
        (uint112 _reserve0, uint112 _reserve1,,) = getReserves(); // gas savings
        address _token0 = token0; // gas savings
        address _token1 = token1; // gas savings
        uint balance0 = IERC20(_token0).balanceOf(address(this));
        uint balance1 = IERC20(_token1).balanceOf(address(this));
        uint liquidity = balanceOf[address(this)];
    
        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        amount0 = liquidity.mul(balance0) / _totalSupply; // using balances ensures pro-rata distribution
        amount1 = liquidity.mul(balance1) / _totalSupply; // using balances ensures pro-rata distribution
        require(amount0 > 0 && amount1 > 0, 'CamelotPair: INSUFFICIENT_LIQUIDITY_BURNED');
        _burn(address(this), liquidity);
        _safeTransfer(_token0, to, amount0);
        _safeTransfer(_token1, to, amount1);
        balance0 = IERC20(_token0).balanceOf(address(this));
        balance1 = IERC20(_token1).balanceOf(address(this));
    
        _update(balance0, balance1);
        if (feeOn) kLast = _k(uint(reserve0), uint(reserve1)); // reserve0 and reserve1 are up-to-date
        emit Burn(msg.sender, amount0, amount1, to);
      }
    
      struct TokensData {
        address token0;
        address token1;
        uint amount0Out;
        uint amount1Out;
        uint balance0;
        uint balance1;
        uint remainingFee0;
        uint remainingFee1;
      }
    
      // this low-level function should be called from a contract which performs important safety checks
      function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external {
        TokensData memory tokensData = TokensData({
          token0: token0,
          token1: token1,
          amount0Out: amount0Out,
          amount1Out: amount1Out,
          balance0: 0,
          balance1: 0,
          remainingFee0: 0,
          remainingFee1: 0
        });
        _swap(tokensData, to, data, address(0));
      }
    
      // this low-level function should be called from a contract which performs important safety checks
      function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data, address referrer) external {
        TokensData memory tokensData = TokensData({
          token0: token0,
          token1: token1,
          amount0Out: amount0Out,
          amount1Out: amount1Out,
          balance0: 0,
          balance1: 0,
          remainingFee0: 0,
          remainingFee1: 0
        });
        _swap(tokensData, to, data, referrer);
      }
    
    
      function _swap(TokensData memory tokensData, address to, bytes memory data, address referrer) internal lock {
        require(tokensData.amount0Out > 0 || tokensData.amount1Out > 0, 'CamelotPair: INSUFFICIENT_OUTPUT_AMOUNT');
    
        (uint112 _reserve0, uint112 _reserve1, uint16 _token0FeePercent, uint16 _token1FeePercent) = getReserves();
        require(tokensData.amount0Out < _reserve0 && tokensData.amount1Out < _reserve1, 'CamelotPair: INSUFFICIENT_LIQUIDITY');
    
    
        {
          require(to != tokensData.token0 && to != tokensData.token1, 'CamelotPair: INVALID_TO');
          // optimistically transfer tokens
          if (tokensData.amount0Out > 0) _safeTransfer(tokensData.token0, to, tokensData.amount0Out);
          // optimistically transfer tokens
          if (tokensData.amount1Out > 0) _safeTransfer(tokensData.token1, to, tokensData.amount1Out);
          if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(msg.sender, tokensData.amount0Out, tokensData.amount1Out, data);
          tokensData.balance0 = IERC20(tokensData.token0).balanceOf(address(this));
          tokensData.balance1 = IERC20(tokensData.token1).balanceOf(address(this));
        }
    
        uint amount0In = tokensData.balance0 > _reserve0 - tokensData.amount0Out ? tokensData.balance0 - (_reserve0 - tokensData.amount0Out) : 0;
        uint amount1In = tokensData.balance1 > _reserve1 - tokensData.amount1Out ? tokensData.balance1 - (_reserve1 - tokensData.amount1Out) : 0;
        require(amount0In > 0 || amount1In > 0, 'CamelotPair: INSUFFICIENT_INPUT_AMOUNT');
    
        tokensData.remainingFee0 = amount0In.mul(_token0FeePercent) / FEE_DENOMINATOR;
        tokensData.remainingFee1 = amount1In.mul(_token1FeePercent) / FEE_DENOMINATOR;
    
        {// scope for referer/stable fees management
          uint fee = 0;
    
          uint referrerInputFeeShare = referrer != address(0) ? ICamelotFactory(factory).referrersFeeShare(referrer) : 0;
          if (referrerInputFeeShare > 0) {
            if (amount0In > 0) {
              fee = amount0In.mul(referrerInputFeeShare).mul(_token0FeePercent) / (FEE_DENOMINATOR ** 2);
              tokensData.remainingFee0 = tokensData.remainingFee0.sub(fee);
              _safeTransfer(tokensData.token0, referrer, fee);
            }
            if (amount1In > 0) {
              fee = amount1In.mul(referrerInputFeeShare).mul(_token1FeePercent) / (FEE_DENOMINATOR ** 2);
              tokensData.remainingFee1 = tokensData.remainingFee1.sub(fee);
              _safeTransfer(tokensData.token1, referrer, fee);
            }
          }
    
          if(stableSwap){
            (uint ownerFeeShare, address feeTo) = ICamelotFactory(factory).feeInfo();
            if(feeTo != address(0)) {
              ownerFeeShare = FEE_DENOMINATOR.sub(referrerInputFeeShare).mul(ownerFeeShare);
              if (amount0In > 0) {
                fee = amount0In.mul(ownerFeeShare).mul(_token0FeePercent) / (FEE_DENOMINATOR ** 3);
                tokensData.remainingFee0 = tokensData.remainingFee0.sub(fee);
                _safeTransfer(tokensData.token0, feeTo, fee);
              }
              if (amount1In > 0) {
                fee = amount1In.mul(ownerFeeShare).mul(_token1FeePercent) / (FEE_DENOMINATOR ** 3);
                tokensData.remainingFee1 = tokensData.remainingFee1.sub(fee);
                _safeTransfer(tokensData.token1, feeTo, fee);
              }
            }
          }
          // readjust tokens balance
          if (amount0In > 0) tokensData.balance0 = IERC20(tokensData.token0).balanceOf(address(this));
          if (amount1In > 0) tokensData.balance1 = IERC20(tokensData.token1).balanceOf(address(this));
        }
        {// scope for reserve{0,1}Adjusted, avoids stack too deep errors
          uint balance0Adjusted = tokensData.balance0.sub(tokensData.remainingFee0);
          uint balance1Adjusted = tokensData.balance1.sub(tokensData.remainingFee1);
          require(_k(balance0Adjusted, balance1Adjusted) >= _k(uint(_reserve0), uint(_reserve1)), 'CamelotPair: K');
        }
        _update(tokensData.balance0, tokensData.balance1);
        emit Swap(msg.sender, amount0In, amount1In, tokensData.amount0Out, tokensData.amount1Out, to);
      }
    
      function _k(uint balance0, uint balance1) internal view returns (uint) {
        if (stableSwap) {
          uint _x = balance0.mul(1e18) / precisionMultiplier0;
          uint _y = balance1.mul(1e18) / precisionMultiplier1;
          uint _a = (_x.mul(_y)) / 1e18;
          uint _b = (_x.mul(_x) / 1e18).add(_y.mul(_y) / 1e18);
          return  _a.mul(_b) / 1e18; // x3y+y3x >= k
        }
        return balance0.mul(balance1);
      }
    
      function _get_y(uint x0, uint xy, uint y) internal pure returns (uint) {
        for (uint i = 0; i < 255; i++) {
          uint y_prev = y;
          uint k = _f(x0, y);
          if (k < xy) {
            uint dy = (xy - k) * 1e18 / _d(x0, y);
            y = y + dy;
          } else {
            uint dy = (k - xy) * 1e18 / _d(x0, y);
            y = y - dy;
          }
          if (y > y_prev) {
            if (y - y_prev <= 1) {
              return y;
            }
          } else {
            if (y_prev - y <= 1) {
              return y;
            }
          }
        }
        return y;
      }
    
      function _f(uint x0, uint y) internal pure returns (uint) {
        return x0 * (y * y / 1e18 * y / 1e18) / 1e18 + (x0 * x0 / 1e18 * x0 / 1e18) * y / 1e18;
      }
    
      function _d(uint x0, uint y) internal pure returns (uint) {
        return 3 * x0 * (y * y / 1e18) / 1e18 + (x0 * x0 / 1e18 * x0 / 1e18);
      }
    
      function getAmountOut(uint amountIn, address tokenIn) external view returns (uint) {
        uint16 feePercent = tokenIn == token0 ? token0FeePercent : token1FeePercent;
        return _getAmountOut(amountIn, tokenIn, uint(reserve0), uint(reserve1), feePercent);
      }
    
      function _getAmountOut(uint amountIn, address tokenIn, uint _reserve0, uint _reserve1, uint feePercent) internal view returns (uint) {
        if (stableSwap) {
          amountIn = amountIn.sub(amountIn.mul(feePercent) / FEE_DENOMINATOR); // remove fee from amount received
          uint xy = _k(_reserve0, _reserve1);
          _reserve0 = _reserve0 * 1e18 / precisionMultiplier0;
          _reserve1 = _reserve1 * 1e18 / precisionMultiplier1;
    
          (uint reserveA, uint reserveB) = tokenIn == token0 ? (_reserve0, _reserve1) : (_reserve1, _reserve0);
          amountIn = tokenIn == token0 ? amountIn * 1e18 / precisionMultiplier0 : amountIn * 1e18 / precisionMultiplier1;
          uint y = reserveB - _get_y(amountIn + reserveA, xy, reserveB);
          return y * (tokenIn == token0 ? precisionMultiplier1 : precisionMultiplier0) / 1e18;
    
        } else {
          (uint reserveA, uint reserveB) = tokenIn == token0 ? (_reserve0, _reserve1) : (_reserve1, _reserve0);
          amountIn = amountIn.mul(FEE_DENOMINATOR.sub(feePercent));
          return (amountIn.mul(reserveB)) / (reserveA.mul(FEE_DENOMINATOR).add(amountIn));
        }
      }
    
      // force balances to match reserves
      function skim(address to) external lock {
        address _token0 = token0;
        // gas savings
        address _token1 = token1;
        // gas savings
        _safeTransfer(_token0, to, IERC20(_token0).balanceOf(address(this)).sub(reserve0));
        _safeTransfer(_token1, to, IERC20(_token1).balanceOf(address(this)).sub(reserve1));
        emit Skim();
      }
    
      // force reserves to match balances
      function sync() external lock {
        uint token0Balance = IERC20(token0).balanceOf(address(this));
        uint token1Balance = IERC20(token1).balanceOf(address(this));
        require(token0Balance != 0 && token1Balance != 0, "CamelotPair: liquidity ratio not initialized");
        _update(token0Balance, token1Balance);
      }
    
      /**
      * @dev Allow to recover token sent here by mistake
      *
      * Can only be called by factory's owner
      */
      function drainWrongToken(address token, address to) external lock {
        require(msg.sender == ICamelotFactory(factory).owner(), "CamelotPair: only factory's owner");
        require(token != token0 && token != token1, "CamelotPair: invalid token");
        _safeTransfer(token, to, IERC20(token).balanceOf(address(this)));
        emit DrainWrongToken(token, to);
      }
    }

    pragma solidity >=0.5.0;
    
    interface ICamelotFactory {
        event PairCreated(address indexed token0, address indexed token1, address pair, uint256);
    
        function owner() external view returns (address);
        function feePercentOwner() external view returns (address);
        function setStableOwner() external view returns (address);
        function feeTo() external view returns (address);
    
        function ownerFeeShare() external view returns (uint256);
        function referrersFeeShare(address) external view returns (uint256);
    
        function getPair(address tokenA, address tokenB) external view returns (address pair);
        function allPairs(uint256) external view returns (address pair);
        function allPairsLength() external view returns (uint256);
    
        function createPair(address tokenA, address tokenB) external returns (address pair);
    
        function setFeeTo(address) external;
        function feeInfo() external view returns (uint _ownerFeeShare, address _feeTo);
    }

    pragma solidity >=0.5.0;
    
    interface ICamelotPair {
        event Approval(address indexed owner, address indexed spender, uint value);
        event Transfer(address indexed from, address indexed to, uint value);
    
        function name() external pure returns (string memory);
        function symbol() external pure returns (string memory);
        function decimals() external pure returns (uint8);
        function totalSupply() external view returns (uint);
        function balanceOf(address owner) external view returns (uint);
        function allowance(address owner, address spender) external view returns (uint);
    
        function approve(address spender, uint value) external returns (bool);
        function transfer(address to, uint value) external returns (bool);
        function transferFrom(address from, address to, uint value) external returns (bool);
    
        function DOMAIN_SEPARATOR() external view returns (bytes32);
        function PERMIT_TYPEHASH() external pure returns (bytes32);
        function nonces(address owner) external view returns (uint);
    
        function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
    
        event Mint(address indexed sender, uint amount0, uint amount1);
        event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
        event Swap(
            address indexed sender,
            uint amount0In,
            uint amount1In,
            uint amount0Out,
            uint amount1Out,
            address indexed to
        );
        event Sync(uint112 reserve0, uint112 reserve1);
    
        function MINIMUM_LIQUIDITY() external pure returns (uint);
        function factory() external view returns (address);
        function token0() external view returns (address);
        function token1() external view returns (address);
        function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint16 token0feePercent, uint16 token1FeePercent);
        function getAmountOut(uint amountIn, address tokenIn) external view returns (uint);
        function kLast() external view returns (uint);
    
        function setFeePercent(uint16 token0FeePercent, uint16 token1FeePercent) external;
        function mint(address to) external returns (uint liquidity);
        function burn(address to) external returns (uint amount0, uint amount1);
        function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
        function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data, address referrer) external;
        function skim(address to) external;
        function sync() external;
    
        function initialize(address, address) external;
    }

    pragma solidity >=0.5.0;
    
    interface IERC20 {
        event Approval(address indexed owner, address indexed spender, uint value);
        event Transfer(address indexed from, address indexed to, uint value);
    
        function name() external view returns (string memory);
        function symbol() external view returns (string memory);
        function decimals() external view returns (uint8);
        function totalSupply() external view returns (uint);
        function balanceOf(address owner) external view returns (uint);
        function allowance(address owner, address spender) external view returns (uint);
    
        function approve(address spender, uint value) external returns (bool);
        function transfer(address to, uint value) external returns (bool);
        function transferFrom(address from, address to, uint value) external returns (bool);
    }

    pragma solidity >=0.5.0;
    
    interface IUniswapV2Callee {
        function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
    }

    pragma solidity >=0.5.0;
    
    interface IUniswapV2ERC20 {
        event Approval(address indexed owner, address indexed spender, uint value);
        event Transfer(address indexed from, address indexed to, uint value);
    
        function name() external pure returns (string memory);
        function symbol() external pure returns (string memory);
        function decimals() external pure returns (uint8);
        function totalSupply() external view returns (uint);
        function balanceOf(address owner) external view returns (uint);
        function allowance(address owner, address spender) external view returns (uint);
    
        function approve(address spender, uint value) external returns (bool);
        function transfer(address to, uint value) external returns (bool);
        function transferFrom(address from, address to, uint value) external returns (bool);
    
        function DOMAIN_SEPARATOR() external view returns (bytes32);
        function PERMIT_TYPEHASH() external pure returns (bytes32);
        function nonces(address owner) external view returns (uint);
    
        function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
    }

    pragma solidity =0.5.16;
    
    // a library for performing various math operations
    
    library Math {
        function min(uint x, uint y) internal pure returns (uint z) {
            z = x < y ? x : y;
        }
    
        // babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
        function sqrt(uint y) internal pure returns (uint z) {
            if (y > 3) {
                z = y;
                uint x = y / 2 + 1;
                while (x < z) {
                    z = x;
                    x = (y / x + x) / 2;
                }
            } else if (y != 0) {
                z = 1;
            }
        }
    }

    pragma solidity =0.5.16;
    
    // a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)
    
    library SafeMath {
        function add(uint x, uint y) internal pure returns (uint z) {
            require((z = x + y) >= x, 'ds-math-add-overflow');
        }
    
        function sub(uint x, uint y) internal pure returns (uint z) {
            require((z = x - y) <= x, 'ds-math-sub-underflow');
        }
    
        function mul(uint x, uint y) internal pure returns (uint z) {
            require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
        }
    }

    pragma solidity =0.5.16;
    
    import './interfaces/IUniswapV2ERC20.sol';
    import './libraries/SafeMath.sol';
    
    contract UniswapV2ERC20 is IUniswapV2ERC20 {
        using SafeMath for uint;
    
        string public constant name = 'Camelot LP';
        string public constant symbol = 'CMLT-LP';
        uint8 public constant decimals = 18;
        uint  public totalSupply;
        mapping(address => uint) public balanceOf;
        mapping(address => mapping(address => uint)) public allowance;
    
        bytes32 public DOMAIN_SEPARATOR;
        // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
        bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
        mapping(address => uint) public nonces;
    
        event Approval(address indexed owner, address indexed spender, uint value);
        event Transfer(address indexed from, address indexed to, uint value);
    
        constructor() public {
            uint chainId;
            assembly {
                chainId := chainid
            }
            DOMAIN_SEPARATOR = keccak256(
                abi.encode(
                    keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                    keccak256(bytes(name)),
                    keccak256(bytes('1')),
                    chainId,
                    address(this)
                )
            );
        }
    
        function _mint(address to, uint value) internal {
            totalSupply = totalSupply.add(value);
            balanceOf[to] = balanceOf[to].add(value);
            emit Transfer(address(0), to, value);
        }
    
        function _burn(address from, uint value) internal {
            balanceOf[from] = balanceOf[from].sub(value);
            totalSupply = totalSupply.sub(value);
            emit Transfer(from, address(0), value);
        }
    
        function _approve(address owner, address spender, uint value) private {
            allowance[owner][spender] = value;
            emit Approval(owner, spender, value);
        }
    
        function _transfer(address from, address to, uint value) private {
            balanceOf[from] = balanceOf[from].sub(value);
            balanceOf[to] = balanceOf[to].add(value);
            emit Transfer(from, to, value);
        }
    
        function approve(address spender, uint value) external returns (bool) {
            _approve(msg.sender, spender, value);
            return true;
        }
    
        function transfer(address to, uint value) external returns (bool) {
            _transfer(msg.sender, to, value);
            return true;
        }
    
        function transferFrom(address from, address to, uint value) external returns (bool) {
            if (allowance[from][msg.sender] != uint(-1)) {
                uint remaining = allowance[from][msg.sender].sub(value);
                allowance[from][msg.sender] = remaining;
                emit Approval(from, msg.sender, remaining);
            }
            _transfer(from, to, value);
            return true;
        }
    
        function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
            require(deadline >= block.timestamp, 'UniswapV2: EXPIRED');
            bytes32 digest = keccak256(
                abi.encodePacked(
                    '\x19\x01',
                    DOMAIN_SEPARATOR,
                    keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
                )
            );
            address recoveredAddress = ecrecover(digest, v, r, s);
            require(recoveredAddress != address(0) && recoveredAddress == owner, 'UniswapV2: INVALID_SIGNATURE');
            _approve(owner, spender, value);
        }
    }

    Context size (optional):