creation_sourcecode: // File: contracts/interfaces/IUniswapV2Pair.sol
  
  pragma solidity >=0.5.0;
  
  interface IUniswapV2Pair {
      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, uint32 blockTimestampLast);
      function price0CumulativeLast() external view returns (uint);
      function price1CumulativeLast() external view returns (uint);
      function kLast() external view returns (uint);
  
      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 skim(address to) external;
      function sync() external;
  
      function initialize(address, address) external;
  }
  
  // File: contracts/interfaces/IUniswapV2ERC20.sol
  
  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;
  }
  
  // File: contracts/libraries/SafeMath.sol
  
  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');
      }
  }
  
  // File: contracts/UniswapV2ERC20.sol
  
  pragma solidity =0.5.16;
  
  
  
  contract UniswapV2ERC20 is IUniswapV2ERC20 {
      using SafeMath for uint;
  
      string public constant name = 'Uniswap V2';
      string public constant symbol = 'UNI-V2';
      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)) {
              allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
          }
          _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);
      }
  }
  
  // File: contracts/libraries/Math.sol
  
  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;
          }
      }
  }
  
  // File: contracts/libraries/UQ112x112.sol
  
  pragma solidity =0.5.16;
  
  // a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))
  
  // range: [0, 2**112 - 1]
  // resolution: 1 / 2**112
  
  library UQ112x112 {
      uint224 constant Q112 = 2**112;
  
      // encode a uint112 as a UQ112x112
      function encode(uint112 y) internal pure returns (uint224 z) {
          z = uint224(y) * Q112; // never overflows
      }
  
      // divide a UQ112x112 by a uint112, returning a UQ112x112
      function uqdiv(uint224 x, uint112 y) internal pure returns (uint224 z) {
          z = x / uint224(y);
      }
  }
  
  // File: contracts/interfaces/IERC20.sol
  
  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);
  }
  
  // File: contracts/interfaces/IUniswapV2Factory.sol
  
  pragma solidity >=0.5.0;
  
  interface IUniswapV2Factory {
      event PairCreated(address indexed token0, address indexed token1, address pair, uint);
  
      function feeTo() external view returns (address);
      function feeToSetter() external view returns (address);
  
      function getPair(address tokenA, address tokenB) external view returns (address pair);
      function allPairs(uint) external view returns (address pair);
      function allPairsLength() external view returns (uint);
  
      function createPair(address tokenA, address tokenB) external returns (address pair);
  
      function setFeeTo(address) external;
      function setFeeToSetter(address) external;
  }
  
  // File: contracts/interfaces/IUniswapV2Callee.sol
  
  pragma solidity >=0.5.0;
  
  interface IUniswapV2Callee {
      function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
  }
  
  // File: contracts/UniswapV2Pair.sol
  
  pragma solidity =0.5.16;
  
  
  
  
  
  
  
  
  contract UniswapV2Pair is IUniswapV2Pair, UniswapV2ERC20 {
      using SafeMath  for uint;
      using UQ112x112 for uint224;
  
      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;
  
      uint112 private reserve0;           // uses single storage slot, accessible via getReserves
      uint112 private reserve1;           // uses single storage slot, accessible via getReserves
      uint32  private blockTimestampLast; // uses single storage slot, accessible via getReserves
  
      uint public price0CumulativeLast;
      uint public price1CumulativeLast;
      uint public kLast; // reserve0 * reserve1, as of immediately after the most recent liquidity event
  
      uint private unlocked = 1;
      modifier lock() {
          require(unlocked == 1, 'UniswapV2: LOCKED');
          unlocked = 0;
          _;
          unlocked = 1;
      }
  
      function getReserves() public view returns (uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast) {
          _reserve0 = reserve0;
          _reserve1 = reserve1;
          _blockTimestampLast = blockTimestampLast;
      }
  
      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))), 'UniswapV2: TRANSFER_FAILED');
      }
  
      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);
  
      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, 'UniswapV2: FORBIDDEN'); // sufficient check
          token0 = _token0;
          token1 = _token1;
      }
  
      // update reserves and, on the first call per block, price accumulators
      function _update(uint balance0, uint balance1, uint112 _reserve0, uint112 _reserve1) private {
          require(balance0 <= uint112(-1) && balance1 <= uint112(-1), 'UniswapV2: OVERFLOW');
          uint32 blockTimestamp = uint32(block.timestamp % 2**32);
          uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired
          if (timeElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
              // * never overflows, and + overflow is desired
              price0CumulativeLast += uint(UQ112x112.encode(_reserve1).uqdiv(_reserve0)) * timeElapsed;
              price1CumulativeLast += uint(UQ112x112.encode(_reserve0).uqdiv(_reserve1)) * timeElapsed;
          }
          reserve0 = uint112(balance0);
          reserve1 = uint112(balance1);
          blockTimestampLast = blockTimestamp;
          emit Sync(reserve0, reserve1);
      }
  
      // if fee is on, mint liquidity equivalent to 1/6th of the growth in sqrt(k)
      function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
          address feeTo = IUniswapV2Factory(factory).feeTo();
          feeOn = feeTo != address(0);
          uint _kLast = kLast; // gas savings
          if (feeOn) {
              if (_kLast != 0) {
                  uint rootK = Math.sqrt(uint(_reserve0).mul(_reserve1));
                  uint rootKLast = Math.sqrt(_kLast);
                  if (rootK > rootKLast) {
                      uint numerator = totalSupply.mul(rootK.sub(rootKLast));
                      uint denominator = rootK.mul(5).add(rootKLast);
                      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, 'UniswapV2: INSUFFICIENT_LIQUIDITY_MINTED');
          _mint(to, liquidity);
  
          _update(balance0, balance1, _reserve0, _reserve1);
          if (feeOn) kLast = uint(reserve0).mul(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, 'UniswapV2: 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, _reserve0, _reserve1);
          if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
          emit Burn(msg.sender, amount0, amount1, to);
      }
  
      // 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 lock {
          require(amount0Out > 0 || amount1Out > 0, 'UniswapV2: INSUFFICIENT_OUTPUT_AMOUNT');
          (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
          require(amount0Out < _reserve0 && amount1Out < _reserve1, 'UniswapV2: INSUFFICIENT_LIQUIDITY');
  
          uint balance0;
          uint balance1;
          { // scope for _token{0,1}, avoids stack too deep errors
          address _token0 = token0;
          address _token1 = token1;
          require(to != _token0 && to != _token1, 'UniswapV2: INVALID_TO');
          if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out); // optimistically transfer tokens
          if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out); // optimistically transfer tokens
          if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(msg.sender, amount0Out, amount1Out, data);
          balance0 = IERC20(_token0).balanceOf(address(this));
          balance1 = IERC20(_token1).balanceOf(address(this));
          }
          uint amount0In = balance0 > _reserve0 - amount0Out ? balance0 - (_reserve0 - amount0Out) : 0;
          uint amount1In = balance1 > _reserve1 - amount1Out ? balance1 - (_reserve1 - amount1Out) : 0;
          require(amount0In > 0 || amount1In > 0, 'UniswapV2: INSUFFICIENT_INPUT_AMOUNT');
          { // scope for reserve{0,1}Adjusted, avoids stack too deep errors
          uint balance0Adjusted = balance0.mul(1000).sub(amount0In.mul(3));
          uint balance1Adjusted = balance1.mul(1000).sub(amount1In.mul(3));
          require(balance0Adjusted.mul(balance1Adjusted) >= uint(_reserve0).mul(_reserve1).mul(1000**2), 'UniswapV2: K');
          }
  
          _update(balance0, balance1, _reserve0, _reserve1);
          emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
      }
  
      // 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));
      }
  
      // force reserves to match balances
      function sync() external lock {
          _update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)), reserve0, reserve1);
      }
  }