pragma solidity =0.6.6;

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;
}

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;
}

interface IUniswapV2Router01 {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}

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);
}

interface IWETH {
    function deposit() external payable;
    function transfer(address to, uint value) external returns (bool);
    function withdraw(uint) external;
}

contract UniswapV2Router02 is IUniswapV2Router02 {
    using SafeMath for uint;

    address public immutable override factory;
    address public immutable override WETH;

    modifier ensure(uint deadline) {
        require(deadline >= block.timestamp, 'UniswapV2Router: EXPIRED');
        _;
    }

    constructor(address _factory, address _WETH) public {
        factory = _factory;
        WETH = _WETH;
    }

    receive() external payable {
        assert(msg.sender == WETH); // only accept ETH via fallback from the WETH contract
    }

    // **** ADD LIQUIDITY ****
    function _addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin
    ) internal virtual returns (uint amountA, uint amountB) {
        // create the pair if it doesn't exist yet
        if (IUniswapV2Factory(factory).getPair(tokenA, tokenB) == address(0)) {
            IUniswapV2Factory(factory).createPair(tokenA, tokenB);
        }
        (uint reserveA, uint reserveB) = UniswapV2Library.getReserves(factory, tokenA, tokenB);
        if (reserveA == 0 && reserveB == 0) {
            (amountA, amountB) = (amountADesired, amountBDesired);
        } else {
            uint amountBOptimal = UniswapV2Library.quote(amountADesired, reserveA, reserveB);
            if (amountBOptimal <= amountBDesired) {
                require(amountBOptimal >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
                (amountA, amountB) = (amountADesired, amountBOptimal);
            } else {
                uint amountAOptimal = UniswapV2Library.quote(amountBDesired, reserveB, reserveA);
                assert(amountAOptimal <= amountADesired);
                require(amountAOptimal >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
                (amountA, amountB) = (amountAOptimal, amountBDesired);
            }
        }
    }
    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) returns (uint amountA, uint amountB, uint liquidity) {
        (amountA, amountB) = _addLiquidity(tokenA, tokenB, amountADesired, amountBDesired, amountAMin, amountBMin);
        address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
        TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);
        TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);
        liquidity = IUniswapV2Pair(pair).mint(to);
    }
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external virtual override payable ensure(deadline) returns (uint amountToken, uint amountETH, uint liquidity) {
        (amountToken, amountETH) = _addLiquidity(
            token,
            WETH,
            amountTokenDesired,
            msg.value,
            amountTokenMin,
            amountETHMin
        );
        address pair = UniswapV2Library.pairFor(factory, token, WETH);
        TransferHelper.safeTransferFrom(token, msg.sender, pair, amountToken);
        IWETH(WETH).deposit{value: amountETH}();
        assert(IWETH(WETH).transfer(pair, amountETH));
        liquidity = IUniswapV2Pair(pair).mint(to);
        // refund dust eth, if any
        if (msg.value > amountETH) TransferHelper.safeTransferETH(msg.sender, msg.value - amountETH);
    }

    // **** REMOVE LIQUIDITY ****
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) public virtual override ensure(deadline) returns (uint amountA, uint amountB) {
        address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
        IUniswapV2Pair(pair).transferFrom(msg.sender, pair, liquidity); // send liquidity to pair
        (uint amount0, uint amount1) = IUniswapV2Pair(pair).burn(to);
        (address token0,) = UniswapV2Library.sortTokens(tokenA, tokenB);
        (amountA, amountB) = tokenA == token0 ? (amount0, amount1) : (amount1, amount0);
        require(amountA >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
        require(amountB >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
    }
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) public virtual override ensure(deadline) returns (uint amountToken, uint amountETH) {
        (amountToken, amountETH) = removeLiquidity(
            token,
            WETH,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        TransferHelper.safeTransfer(token, to, amountToken);
        IWETH(WETH).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, amountETH);
    }
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external virtual override returns (uint amountA, uint amountB) {
        address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        (amountA, amountB) = removeLiquidity(tokenA, tokenB, liquidity, amountAMin, amountBMin, to, deadline);
    }
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external virtual override returns (uint amountToken, uint amountETH) {
        address pair = UniswapV2Library.pairFor(factory, token, WETH);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        (amountToken, amountETH) = removeLiquidityETH(token, liquidity, amountTokenMin, amountETHMin, to, deadline);
    }

    // **** REMOVE LIQUIDITY (supporting fee-on-transfer tokens) ****
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) public virtual override ensure(deadline) returns (uint amountETH) {
        (, amountETH) = removeLiquidity(
            token,
            WETH,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        TransferHelper.safeTransfer(token, to, IERC20(token).balanceOf(address(this)));
        IWETH(WETH).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, amountETH);
    }
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external virtual override returns (uint amountETH) {
        address pair = UniswapV2Library.pairFor(factory, token, WETH);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        amountETH = removeLiquidityETHSupportingFeeOnTransferTokens(
            token, liquidity, amountTokenMin, amountETHMin, to, deadline
        );
    }

    // **** SWAP ****
    // requires the initial amount to have already been sent to the first pair
    function _swap(uint[] memory amounts, address[] memory path, address _to) internal virtual {
        for (uint i; i < path.length - 1; i++) {
            (address input, address output) = (path[i], path[i + 1]);
            (address token0,) = UniswapV2Library.sortTokens(input, output);
            uint amountOut = amounts[i + 1];
            (uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOut) : (amountOut, uint(0));
            address to = i < path.length - 2 ? UniswapV2Library.pairFor(factory, output, path[i + 2]) : _to;
            IUniswapV2Pair(UniswapV2Library.pairFor(factory, input, output)).swap(
                amount0Out, amount1Out, to, new bytes(0)
            );
        }
    }
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) returns (uint[] memory amounts) {
        amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, to);
    }
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) returns (uint[] memory amounts) {
        amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, to);
    }
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        payable
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
        amounts = UniswapV2Library.getAmountsOut(factory, msg.value, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
        IWETH(WETH).deposit{value: amounts[0]}();
        assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]));
        _swap(amounts, path, to);
    }
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
        amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, address(this));
        IWETH(WETH).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
        amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, address(this));
        IWETH(WETH).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        payable
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
        amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= msg.value, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
        IWETH(WETH).deposit{value: amounts[0]}();
        assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]));
        _swap(amounts, path, to);
        // refund dust eth, if any
        if (msg.value > amounts[0]) TransferHelper.safeTransferETH(msg.sender, msg.value - amounts[0]);
    }

    // **** SWAP (supporting fee-on-transfer tokens) ****
    // requires the initial amount to have already been sent to the first pair
    function _swapSupportingFeeOnTransferTokens(address[] memory path, address _to) internal virtual {
        for (uint i; i < path.length - 1; i++) {
            (address input, address output) = (path[i], path[i + 1]);
            (address token0,) = UniswapV2Library.sortTokens(input, output);
            IUniswapV2Pair pair = IUniswapV2Pair(UniswapV2Library.pairFor(factory, input, output));
            uint amountInput;
            uint amountOutput;
            { // scope to avoid stack too deep errors
            (uint reserve0, uint reserve1,) = pair.getReserves();
            (uint reserveInput, uint reserveOutput) = input == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
            amountInput = IERC20(input).balanceOf(address(pair)).sub(reserveInput);
            amountOutput = UniswapV2Library.getAmountOut(amountInput, reserveInput, reserveOutput);
            }
            (uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOutput) : (amountOutput, uint(0));
            address to = i < path.length - 2 ? UniswapV2Library.pairFor(factory, output, path[i + 2]) : _to;
            pair.swap(amount0Out, amount1Out, to, new bytes(0));
        }
    }
    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) {
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn
        );
        uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
        _swapSupportingFeeOnTransferTokens(path, to);
        require(
            IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,
            'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT'
        );
    }
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    )
        external
        virtual
        override
        payable
        ensure(deadline)
    {
        require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
        uint amountIn = msg.value;
        IWETH(WETH).deposit{value: amountIn}();
        assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn));
        uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
        _swapSupportingFeeOnTransferTokens(path, to);
        require(
            IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,
            'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT'
        );
    }
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    )
        external
        virtual
        override
        ensure(deadline)
    {
        require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn
        );
        _swapSupportingFeeOnTransferTokens(path, address(this));
        uint amountOut = IERC20(WETH).balanceOf(address(this));
        require(amountOut >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
        IWETH(WETH).withdraw(amountOut);
        TransferHelper.safeTransferETH(to, amountOut);
    }

    // **** LIBRARY FUNCTIONS ****
    function quote(uint amountA, uint reserveA, uint reserveB) public pure virtual override returns (uint amountB) {
        return UniswapV2Library.quote(amountA, reserveA, reserveB);
    }

    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut)
        public
        pure
        virtual
        override
        returns (uint amountOut)
    {
        return UniswapV2Library.getAmountOut(amountIn, reserveIn, reserveOut);
    }

    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut)
        public
        pure
        virtual
        override
        returns (uint amountIn)
    {
        return UniswapV2Library.getAmountIn(amountOut, reserveIn, reserveOut);
    }

    function getAmountsOut(uint amountIn, address[] memory path)
        public
        view
        virtual
        override
        returns (uint[] memory amounts)
    {
        return UniswapV2Library.getAmountsOut(factory, amountIn, path);
    }

    function getAmountsIn(uint amountOut, address[] memory path)
        public
        view
        virtual
        override
        returns (uint[] memory amounts)
    {
        return UniswapV2Library.getAmountsIn(factory, amountOut, path);
    }
}

// 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');
    }
}

library UniswapV2Library {
    using SafeMath for uint;

    // returns sorted token addresses, used to handle return values from pairs sorted in this order
    function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) {
        require(tokenA != tokenB, 'UniswapV2Library: IDENTICAL_ADDRESSES');
        (token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        require(token0 != address(0), 'UniswapV2Library: ZERO_ADDRESS');
    }

    // calculates the CREATE2 address for a pair without making any external calls
    function pairFor(address factory, address tokenA, address tokenB) internal pure returns (address pair) {
        (address token0, address token1) = sortTokens(tokenA, tokenB);
        pair = address(uint(keccak256(abi.encodePacked(
                hex'ff',
                factory,
                keccak256(abi.encodePacked(token0, token1)),
                hex'96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f' // init code hash
            ))));
    }

    // fetches and sorts the reserves for a pair
    function getReserves(address factory, address tokenA, address tokenB) internal view returns (uint reserveA, uint reserveB) {
        (address token0,) = sortTokens(tokenA, tokenB);
        (uint reserve0, uint reserve1,) = IUniswapV2Pair(pairFor(factory, tokenA, tokenB)).getReserves();
        (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
    }

    // given some amount of an asset and pair reserves, returns an equivalent amount of the other asset
    function quote(uint amountA, uint reserveA, uint reserveB) internal pure returns (uint amountB) {
        require(amountA > 0, 'UniswapV2Library: INSUFFICIENT_AMOUNT');
        require(reserveA > 0 && reserveB > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        amountB = amountA.mul(reserveB) / reserveA;
    }

    // given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) internal pure returns (uint amountOut) {
        require(amountIn > 0, 'UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        uint amountInWithFee = amountIn.mul(997);
        uint numerator = amountInWithFee.mul(reserveOut);
        uint denominator = reserveIn.mul(1000).add(amountInWithFee);
        amountOut = numerator / denominator;
    }

    // given an output amount of an asset and pair reserves, returns a required input amount of the other asset
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) internal pure returns (uint amountIn) {
        require(amountOut > 0, 'UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        uint numerator = reserveIn.mul(amountOut).mul(1000);
        uint denominator = reserveOut.sub(amountOut).mul(997);
        amountIn = (numerator / denominator).add(1);
    }

    // performs chained getAmountOut calculations on any number of pairs
    function getAmountsOut(address factory, uint amountIn, address[] memory path) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[0] = amountIn;
        for (uint i; i < path.length - 1; i++) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i], path[i + 1]);
            amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
        }
    }

    // performs chained getAmountIn calculations on any number of pairs
    function getAmountsIn(address factory, uint amountOut, address[] memory path) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[amounts.length - 1] = amountOut;
        for (uint i = path.length - 1; i > 0; i--) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i - 1], path[i]);
            amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
        }
    }
}

// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
library TransferHelper {
    function safeApprove(address token, address to, uint value) internal {
        // bytes4(keccak256(bytes('approve(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: APPROVE_FAILED');
    }

    function safeTransfer(address token, address to, uint value) internal {
        // bytes4(keccak256(bytes('transfer(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED');
    }

    function safeTransferFrom(address token, address from, address to, uint value) internal {
        // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED');
    }

    function safeTransferETH(address to, uint value) internal {
        (bool success,) = to.call{value:value}(new bytes(0));
        require(success, 'TransferHelper: ETH_TRANSFER_FAILED');
    }
}

// Copyright (C) 2015, 2016, 2017 Dapphub

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.4.18;

contract WETH9 {
    string public name     = "Wrapped Ether";
    string public symbol   = "WETH";
    uint8  public decimals = 18;

    event  Approval(address indexed src, address indexed guy, uint wad);
    event  Transfer(address indexed src, address indexed dst, uint wad);
    event  Deposit(address indexed dst, uint wad);
    event  Withdrawal(address indexed src, uint wad);

    mapping (address => uint)                       public  balanceOf;
    mapping (address => mapping (address => uint))  public  allowance;

    function() public payable {
        deposit();
    }
    function deposit() public payable {
        balanceOf[msg.sender] += msg.value;
        Deposit(msg.sender, msg.value);
    }
    function withdraw(uint wad) public {
        require(balanceOf[msg.sender] >= wad);
        balanceOf[msg.sender] -= wad;
        msg.sender.transfer(wad);
        Withdrawal(msg.sender, wad);
    }

    function totalSupply() public view returns (uint) {
        return this.balance;
    }

    function approve(address guy, uint wad) public returns (bool) {
        allowance[msg.sender][guy] = wad;
        Approval(msg.sender, guy, wad);
        return true;
    }

    function transfer(address dst, uint wad) public returns (bool) {
        return transferFrom(msg.sender, dst, wad);
    }

    function transferFrom(address src, address dst, uint wad)
        public
        returns (bool)
    {
        require(balanceOf[src] >= wad);

        if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
            require(allowance[src][msg.sender] >= wad);
            allowance[src][msg.sender] -= wad;
        }

        balanceOf[src] -= wad;
        balanceOf[dst] += wad;

        Transfer(src, dst, wad);

        return true;
    }
}


/*
                    GNU GENERAL PUBLIC LICENSE
                       Version 3, 29 June 2007

 Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
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            How to Apply These Terms to Your New Programs

  If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.

  To do so, attach the following notices to the program.  It is safest
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    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

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    along with this program.  If not, see <http://www.gnu.org/licenses/>.

Also add information on how to contact you by electronic and paper mail.

  If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:

    <program>  Copyright (C) <year>  <name of author>
    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; type `show c' for details.

The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License.  Of course, your program's commands
might be different; for a GUI interface, you would use an "about box".

  You should also get your employer (if you work as a programmer) or school,
if any, to sign a "copyright disclaimer" for the program, if necessary.
For more information on this, and how to apply and follow the GNU GPL, see
<http://www.gnu.org/licenses/>.

  The GNU General Public License does not permit incorporating your program
into proprietary programs.  If your program is a subroutine library, you
may consider it more useful to permit linking proprietary applications with
the library.  If this is what you want to do, use the GNU Lesser General
Public License instead of this License.  But first, please read
<http://www.gnu.org/philosophy/why-not-lgpl.html>.

*/

// 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);
    }
}

pragma solidity 0.5.13;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20Mintable}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20};
     *
     * Requirements:
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for `sender`'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

     /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: burn from the zero address");

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner`s tokens.
     *
     * This is internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`.`amount` is then deducted
     * from the caller's allowance.
     *
     * See {_burn} and {_approve}.
     */
    function _burnFrom(address account, uint256 amount) internal {
        _burn(account, amount);
        _approve(account, _msgSender(), _allowances[account][_msgSender()].sub(amount, "ERC20: burn amount exceeds allowance"));
    }
}

contract GlobalsAndUtility is ERC20 {
    /*  XfLobbyEnter      (auto-generated event)

        uint40            timestamp       -->  data0 [ 39:  0]
        address  indexed  memberAddr
        uint256  indexed  entryId
        uint96            rawAmount       -->  data0 [135: 40]
        address  indexed  referrerAddr
    */
    event XfLobbyEnter(
        uint256 data0,
        address indexed memberAddr,
        uint256 indexed entryId,
        address indexed referrerAddr
    );

    /*  XfLobbyExit       (auto-generated event)

        uint40            timestamp       -->  data0 [ 39:  0]
        address  indexed  memberAddr
        uint256  indexed  entryId
        uint72            xfAmount        -->  data0 [111: 40]
        address  indexed  referrerAddr
    */
    event XfLobbyExit(
        uint256 data0,
        address indexed memberAddr,
        uint256 indexed entryId,
        address indexed referrerAddr
    );

    /*  DailyDataUpdate   (auto-generated event)

        uint40            timestamp       -->  data0 [ 39:  0]
        uint16            beginDay        -->  data0 [ 55: 40]
        uint16            endDay          -->  data0 [ 71: 56]
        bool              isAutoUpdate    -->  data0 [ 79: 72]
        address  indexed  updaterAddr
    */
    event DailyDataUpdate(
        uint256 data0,
        address indexed updaterAddr
    );

    /*  Claim             (auto-generated event)

        uint40            timestamp       -->  data0 [ 39:  0]
        bytes20  indexed  btcAddr
        uint56            rawSatoshis     -->  data0 [ 95: 40]
        uint56            adjSatoshis     -->  data0 [151: 96]
        address  indexed  claimToAddr
        uint8             claimFlags      -->  data0 [159:152]
        uint72            claimedHearts   -->  data0 [231:160]
        address  indexed  referrerAddr
        address           senderAddr      -->  data1 [159:  0]
    */
    event Claim(
        uint256 data0,
        uint256 data1,
        bytes20 indexed btcAddr,
        address indexed claimToAddr,
        address indexed referrerAddr
    );

    /*  ClaimAssist       (auto-generated event)

        uint40            timestamp       -->  data0 [ 39:  0]
        bytes20           btcAddr         -->  data0 [199: 40]
        uint56            rawSatoshis     -->  data0 [255:200]
        uint56            adjSatoshis     -->  data1 [ 55:  0]
        address           claimToAddr     -->  data1 [215: 56]
        uint8             claimFlags      -->  data1 [223:216]
        uint72            claimedHearts   -->  data2 [ 71:  0]
        address           referrerAddr    -->  data2 [231: 72]
        address  indexed  senderAddr
    */
    event ClaimAssist(
        uint256 data0,
        uint256 data1,
        uint256 data2,
        address indexed senderAddr
    );

    /*  StakeStart        (auto-generated event)

        uint40            timestamp       -->  data0 [ 39:  0]
        address  indexed  stakerAddr
        uint40   indexed  stakeId
        uint72            stakedHearts    -->  data0 [111: 40]
        uint72            stakeShares     -->  data0 [183:112]
        uint16            stakedDays      -->  data0 [199:184]
        bool              isAutoStake     -->  data0 [207:200]
    */
    event StakeStart(
        uint256 data0,
        address indexed stakerAddr,
        uint40 indexed stakeId
    );

    /*  StakeGoodAccounting(auto-generated event)

        uint40            timestamp       -->  data0 [ 39:  0]
        address  indexed  stakerAddr
        uint40   indexed  stakeId
        uint72            stakedHearts    -->  data0 [111: 40]
        uint72            stakeShares     -->  data0 [183:112]
        uint72            payout          -->  data0 [255:184]
        uint72            penalty         -->  data1 [ 71:  0]
        address  indexed  senderAddr
    */
    event StakeGoodAccounting(
        uint256 data0,
        uint256 data1,
        address indexed stakerAddr,
        uint40 indexed stakeId,
        address indexed senderAddr
    );

    /*  StakeEnd          (auto-generated event)

        uint40            timestamp       -->  data0 [ 39:  0]
        address  indexed  stakerAddr
        uint40   indexed  stakeId
        uint72            stakedHearts    -->  data0 [111: 40]
        uint72            stakeShares     -->  data0 [183:112]
        uint72            payout          -->  data0 [255:184]
        uint72            penalty         -->  data1 [ 71:  0]
        uint16            servedDays      -->  data1 [ 87: 72]
        bool              prevUnlocked    -->  data1 [ 95: 88]
    */
    event StakeEnd(
        uint256 data0,
        uint256 data1,
        address indexed stakerAddr,
        uint40 indexed stakeId
    );

    /*  ShareRateChange   (auto-generated event)

        uint40            timestamp       -->  data0 [ 39:  0]
        uint40            shareRate       -->  data0 [ 79: 40]
        uint40   indexed  stakeId
    */
    event ShareRateChange(
        uint256 data0,
        uint40 indexed stakeId
    );

    /* Origin address */
    address internal constant ORIGIN_ADDR = 0x9A6a414D6F3497c05E3b1De90520765fA1E07c03;

    /* Flush address */
    address payable internal constant FLUSH_ADDR = 0xDEC9f2793e3c17cd26eeFb21C4762fA5128E0399;

    /* ERC20 constants */
    string public constant name = "HEX";
    string public constant symbol = "HEX";
    uint8 public constant decimals = 8;

    /* Hearts per Satoshi = 10,000 * 1e8 / 1e8 = 1e4 */
    uint256 private constant HEARTS_PER_HEX = 10 ** uint256(decimals); // 1e8
    uint256 private constant HEX_PER_BTC = 1e4;
    uint256 private constant SATOSHIS_PER_BTC = 1e8;
    uint256 internal constant HEARTS_PER_SATOSHI = HEARTS_PER_HEX / SATOSHIS_PER_BTC * HEX_PER_BTC;

    /* Time of contract launch (2019-12-03T00:00:00Z) */
    uint256 internal constant LAUNCH_TIME = 1575331200;

    /* Size of a Hearts or Shares uint */
    uint256 internal constant HEART_UINT_SIZE = 72;

    /* Size of a transform lobby entry index uint */
    uint256 internal constant XF_LOBBY_ENTRY_INDEX_SIZE = 40;
    uint256 internal constant XF_LOBBY_ENTRY_INDEX_MASK = (1 << XF_LOBBY_ENTRY_INDEX_SIZE) - 1;

    /* Seed for WAAS Lobby */
    uint256 internal constant WAAS_LOBBY_SEED_HEX = 1e9;
    uint256 internal constant WAAS_LOBBY_SEED_HEARTS = WAAS_LOBBY_SEED_HEX * HEARTS_PER_HEX;

    /* Start of claim phase */
    uint256 internal constant PRE_CLAIM_DAYS = 1;
    uint256 internal constant CLAIM_PHASE_START_DAY = PRE_CLAIM_DAYS;

    /* Length of claim phase */
    uint256 private constant CLAIM_PHASE_WEEKS = 50;
    uint256 internal constant CLAIM_PHASE_DAYS = CLAIM_PHASE_WEEKS * 7;

    /* End of claim phase */
    uint256 internal constant CLAIM_PHASE_END_DAY = CLAIM_PHASE_START_DAY + CLAIM_PHASE_DAYS;

    /* Number of words to hold 1 bit for each transform lobby day */
    uint256 internal constant XF_LOBBY_DAY_WORDS = (CLAIM_PHASE_END_DAY + 255) >> 8;

    /* BigPayDay */
    uint256 internal constant BIG_PAY_DAY = CLAIM_PHASE_END_DAY + 1;

    /* Root hash of the UTXO Merkle tree */
    bytes32 internal constant MERKLE_TREE_ROOT = 0x4e831acb4223b66de3b3d2e54a2edeefb0de3d7916e2886a4b134d9764d41bec;

    /* Size of a Satoshi claim uint in a Merkle leaf */
    uint256 internal constant MERKLE_LEAF_SATOSHI_SIZE = 45;

    /* Zero-fill between BTC address and Satoshis in a Merkle leaf */
    uint256 internal constant MERKLE_LEAF_FILL_SIZE = 256 - 160 - MERKLE_LEAF_SATOSHI_SIZE;
    uint256 internal constant MERKLE_LEAF_FILL_BASE = (1 << MERKLE_LEAF_FILL_SIZE) - 1;
    uint256 internal constant MERKLE_LEAF_FILL_MASK = MERKLE_LEAF_FILL_BASE << MERKLE_LEAF_SATOSHI_SIZE;

    /* Size of a Satoshi total uint */
    uint256 internal constant SATOSHI_UINT_SIZE = 51;
    uint256 internal constant SATOSHI_UINT_MASK = (1 << SATOSHI_UINT_SIZE) - 1;

    /* Total Satoshis from all BTC addresses in UTXO snapshot */
    uint256 internal constant FULL_SATOSHIS_TOTAL = 1807766732160668;

    /* Total Satoshis from supported BTC addresses in UTXO snapshot after applying Silly Whale */
    uint256 internal constant CLAIMABLE_SATOSHIS_TOTAL = 910087996911001;

    /* Number of claimable BTC addresses in UTXO snapshot */
    uint256 internal constant CLAIMABLE_BTC_ADDR_COUNT = 27997742;

    /* Largest BTC address Satoshis balance in UTXO snapshot (sanity check) */
    uint256 internal constant MAX_BTC_ADDR_BALANCE_SATOSHIS = 25550214098481;

    /* Percentage of total claimed Hearts that will be auto-staked from a claim */
    uint256 internal constant AUTO_STAKE_CLAIM_PERCENT = 90;

    /* Stake timing parameters */
    uint256 internal constant MIN_STAKE_DAYS = 1;
    uint256 internal constant MIN_AUTO_STAKE_DAYS = 350;

    uint256 internal constant MAX_STAKE_DAYS = 5555; // Approx 15 years

    uint256 internal constant EARLY_PENALTY_MIN_DAYS = 90;

    uint256 private constant LATE_PENALTY_GRACE_WEEKS = 2;
    uint256 internal constant LATE_PENALTY_GRACE_DAYS = LATE_PENALTY_GRACE_WEEKS * 7;

    uint256 private constant LATE_PENALTY_SCALE_WEEKS = 100;
    uint256 internal constant LATE_PENALTY_SCALE_DAYS = LATE_PENALTY_SCALE_WEEKS * 7;

    /* Stake shares Longer Pays Better bonus constants used by _stakeStartBonusHearts() */
    uint256 private constant LPB_BONUS_PERCENT = 20;
    uint256 private constant LPB_BONUS_MAX_PERCENT = 200;
    uint256 internal constant LPB = 364 * 100 / LPB_BONUS_PERCENT;
    uint256 internal constant LPB_MAX_DAYS = LPB * LPB_BONUS_MAX_PERCENT / 100;

    /* Stake shares Bigger Pays Better bonus constants used by _stakeStartBonusHearts() */
    uint256 private constant BPB_BONUS_PERCENT = 10;
    uint256 private constant BPB_MAX_HEX = 150 * 1e6;
    uint256 internal constant BPB_MAX_HEARTS = BPB_MAX_HEX * HEARTS_PER_HEX;
    uint256 internal constant BPB = BPB_MAX_HEARTS * 100 / BPB_BONUS_PERCENT;

    /* Share rate is scaled to increase precision */
    uint256 internal constant SHARE_RATE_SCALE = 1e5;

    /* Share rate max (after scaling) */
    uint256 internal constant SHARE_RATE_UINT_SIZE = 40;
    uint256 internal constant SHARE_RATE_MAX = (1 << SHARE_RATE_UINT_SIZE) - 1;

    /* Constants for preparing the claim message text */
    uint8 internal constant ETH_ADDRESS_BYTE_LEN = 20;
    uint8 internal constant ETH_ADDRESS_HEX_LEN = ETH_ADDRESS_BYTE_LEN * 2;

    uint8 internal constant CLAIM_PARAM_HASH_BYTE_LEN = 12;
    uint8 internal constant CLAIM_PARAM_HASH_HEX_LEN = CLAIM_PARAM_HASH_BYTE_LEN * 2;

    uint8 internal constant BITCOIN_SIG_PREFIX_LEN = 24;
    bytes24 internal constant BITCOIN_SIG_PREFIX_STR = "Bitcoin Signed Message:\n";

    bytes internal constant STD_CLAIM_PREFIX_STR = "Claim_HEX_to_0x";
    bytes internal constant OLD_CLAIM_PREFIX_STR = "Claim_BitcoinHEX_to_0x";

    bytes16 internal constant HEX_DIGITS = "0123456789abcdef";

    /* Claim flags passed to btcAddressClaim()  */
    uint8 internal constant CLAIM_FLAG_MSG_PREFIX_OLD = 1 << 0;
    uint8 internal constant CLAIM_FLAG_BTC_ADDR_COMPRESSED = 1 << 1;
    uint8 internal constant CLAIM_FLAG_BTC_ADDR_P2WPKH_IN_P2SH = 1 << 2;
    uint8 internal constant CLAIM_FLAG_BTC_ADDR_BECH32 = 1 << 3;
    uint8 internal constant CLAIM_FLAG_ETH_ADDR_LOWERCASE = 1 << 4;

    /* Globals expanded for memory (except _latestStakeId) and compact for storage */
    struct GlobalsCache {
        // 1
        uint256 _lockedHeartsTotal;
        uint256 _nextStakeSharesTotal;
        uint256 _shareRate;
        uint256 _stakePenaltyTotal;
        // 2
        uint256 _dailyDataCount;
        uint256 _stakeSharesTotal;
        uint40 _latestStakeId;
        uint256 _unclaimedSatoshisTotal;
        uint256 _claimedSatoshisTotal;
        uint256 _claimedBtcAddrCount;
        //
        uint256 _currentDay;
    }

    struct GlobalsStore {
        // 1
        uint72 lockedHeartsTotal;
        uint72 nextStakeSharesTotal;
        uint40 shareRate;
        uint72 stakePenaltyTotal;
        // 2
        uint16 dailyDataCount;
        uint72 stakeSharesTotal;
        uint40 latestStakeId;
        uint128 claimStats;
    }

    GlobalsStore public globals;

    /* Claimed BTC addresses */
    mapping(bytes20 => bool) public btcAddressClaims;

    /* Daily data */
    struct DailyDataStore {
        uint72 dayPayoutTotal;
        uint72 dayStakeSharesTotal;
        uint56 dayUnclaimedSatoshisTotal;
    }

    mapping(uint256 => DailyDataStore) public dailyData;

    /* Stake expanded for memory (except _stakeId) and compact for storage */
    struct StakeCache {
        uint40 _stakeId;
        uint256 _stakedHearts;
        uint256 _stakeShares;
        uint256 _lockedDay;
        uint256 _stakedDays;
        uint256 _unlockedDay;
        bool _isAutoStake;
    }

    struct StakeStore {
        uint40 stakeId;
        uint72 stakedHearts;
        uint72 stakeShares;
        uint16 lockedDay;
        uint16 stakedDays;
        uint16 unlockedDay;
        bool isAutoStake;
    }

    mapping(address => StakeStore[]) public stakeLists;

    /* Temporary state for calculating daily rounds */
    struct DailyRoundState {
        uint256 _allocSupplyCached;
        uint256 _mintOriginBatch;
        uint256 _payoutTotal;
    }

    struct XfLobbyEntryStore {
        uint96 rawAmount;
        address referrerAddr;
    }

    struct XfLobbyQueueStore {
        uint40 headIndex;
        uint40 tailIndex;
        mapping(uint256 => XfLobbyEntryStore) entries;
    }

    mapping(uint256 => uint256) public xfLobby;
    mapping(uint256 => mapping(address => XfLobbyQueueStore)) public xfLobbyMembers;

    /**
     * @dev PUBLIC FACING: Optionally update daily data for a smaller
     * range to reduce gas cost for a subsequent operation
     * @param beforeDay Only update days before this day number (optional; 0 for current day)
     */
    function dailyDataUpdate(uint256 beforeDay)
        external
    {
        GlobalsCache memory g;
        GlobalsCache memory gSnapshot;
        _globalsLoad(g, gSnapshot);

        /* Skip pre-claim period */
        require(g._currentDay > CLAIM_PHASE_START_DAY, "HEX: Too early");

        if (beforeDay != 0) {
            require(beforeDay <= g._currentDay, "HEX: beforeDay cannot be in the future");

            _dailyDataUpdate(g, beforeDay, false);
        } else {
            /* Default to updating before current day */
            _dailyDataUpdate(g, g._currentDay, false);
        }

        _globalsSync(g, gSnapshot);
    }

    /**
     * @dev PUBLIC FACING: External helper to return multiple values of daily data with
     * a single call. Ugly implementation due to limitations of the standard ABI encoder.
     * @param beginDay First day of data range
     * @param endDay Last day (non-inclusive) of data range
     * @return Fixed array of packed values
     */
    function dailyDataRange(uint256 beginDay, uint256 endDay)
        external
        view
        returns (uint256[] memory list)
    {
        require(beginDay < endDay && endDay <= globals.dailyDataCount, "HEX: range invalid");

        list = new uint256[](endDay - beginDay);

        uint256 src = beginDay;
        uint256 dst = 0;
        uint256 v;
        do {
            v = uint256(dailyData[src].dayUnclaimedSatoshisTotal) << (HEART_UINT_SIZE * 2);
            v |= uint256(dailyData[src].dayStakeSharesTotal) << HEART_UINT_SIZE;
            v |= uint256(dailyData[src].dayPayoutTotal);

            list[dst++] = v;
        } while (++src < endDay);

        return list;
    }

    /**
     * @dev PUBLIC FACING: External helper to return most global info with a single call.
     * Ugly implementation due to limitations of the standard ABI encoder.
     * @return Fixed array of values
     */
    function globalInfo()
        external
        view
        returns (uint256[13] memory)
    {
        uint256 _claimedBtcAddrCount;
        uint256 _claimedSatoshisTotal;
        uint256 _unclaimedSatoshisTotal;

        (_claimedBtcAddrCount, _claimedSatoshisTotal, _unclaimedSatoshisTotal) = _claimStatsDecode(
            globals.claimStats
        );

        return [
            // 1
            globals.lockedHeartsTotal,
            globals.nextStakeSharesTotal,
            globals.shareRate,
            globals.stakePenaltyTotal,
            // 2
            globals.dailyDataCount,
            globals.stakeSharesTotal,
            globals.latestStakeId,
            _unclaimedSatoshisTotal,
            _claimedSatoshisTotal,
            _claimedBtcAddrCount,
            //
            block.timestamp,
            totalSupply(),
            xfLobby[_currentDay()]
        ];
    }

    /**
     * @dev PUBLIC FACING: ERC20 totalSupply() is the circulating supply and does not include any
     * staked Hearts. allocatedSupply() includes both.
     * @return Allocated Supply in Hearts
     */
    function allocatedSupply()
        external
        view
        returns (uint256)
    {
        return totalSupply() + globals.lockedHeartsTotal;
    }

    /**
     * @dev PUBLIC FACING: External helper for the current day number since launch time
     * @return Current day number (zero-based)
     */
    function currentDay()
        external
        view
        returns (uint256)
    {
        return _currentDay();
    }

    function _currentDay()
        internal
        view
        returns (uint256)
    {
        return (block.timestamp - LAUNCH_TIME) / 1 days;
    }

    function _dailyDataUpdateAuto(GlobalsCache memory g)
        internal
    {
        _dailyDataUpdate(g, g._currentDay, true);
    }

    function _globalsLoad(GlobalsCache memory g, GlobalsCache memory gSnapshot)
        internal
        view
    {
        // 1
        g._lockedHeartsTotal = globals.lockedHeartsTotal;
        g._nextStakeSharesTotal = globals.nextStakeSharesTotal;
        g._shareRate = globals.shareRate;
        g._stakePenaltyTotal = globals.stakePenaltyTotal;
        // 2
        g._dailyDataCount = globals.dailyDataCount;
        g._stakeSharesTotal = globals.stakeSharesTotal;
        g._latestStakeId = globals.latestStakeId;
        (g._claimedBtcAddrCount, g._claimedSatoshisTotal, g._unclaimedSatoshisTotal) = _claimStatsDecode(
            globals.claimStats
        );
        //
        g._currentDay = _currentDay();

        _globalsCacheSnapshot(g, gSnapshot);
    }

    function _globalsCacheSnapshot(GlobalsCache memory g, GlobalsCache memory gSnapshot)
        internal
        pure
    {
        // 1
        gSnapshot._lockedHeartsTotal = g._lockedHeartsTotal;
        gSnapshot._nextStakeSharesTotal = g._nextStakeSharesTotal;
        gSnapshot._shareRate = g._shareRate;
        gSnapshot._stakePenaltyTotal = g._stakePenaltyTotal;
        // 2
        gSnapshot._dailyDataCount = g._dailyDataCount;
        gSnapshot._stakeSharesTotal = g._stakeSharesTotal;
        gSnapshot._latestStakeId = g._latestStakeId;
        gSnapshot._unclaimedSatoshisTotal = g._unclaimedSatoshisTotal;
        gSnapshot._claimedSatoshisTotal = g._claimedSatoshisTotal;
        gSnapshot._claimedBtcAddrCount = g._claimedBtcAddrCount;
    }

    function _globalsSync(GlobalsCache memory g, GlobalsCache memory gSnapshot)
        internal
    {
        if (g._lockedHeartsTotal != gSnapshot._lockedHeartsTotal
            || g._nextStakeSharesTotal != gSnapshot._nextStakeSharesTotal
            || g._shareRate != gSnapshot._shareRate
            || g._stakePenaltyTotal != gSnapshot._stakePenaltyTotal) {
            // 1
            globals.lockedHeartsTotal = uint72(g._lockedHeartsTotal);
            globals.nextStakeSharesTotal = uint72(g._nextStakeSharesTotal);
            globals.shareRate = uint40(g._shareRate);
            globals.stakePenaltyTotal = uint72(g._stakePenaltyTotal);
        }
        if (g._dailyDataCount != gSnapshot._dailyDataCount
            || g._stakeSharesTotal != gSnapshot._stakeSharesTotal
            || g._latestStakeId != gSnapshot._latestStakeId
            || g._unclaimedSatoshisTotal != gSnapshot._unclaimedSatoshisTotal
            || g._claimedSatoshisTotal != gSnapshot._claimedSatoshisTotal
            || g._claimedBtcAddrCount != gSnapshot._claimedBtcAddrCount) {
            // 2
            globals.dailyDataCount = uint16(g._dailyDataCount);
            globals.stakeSharesTotal = uint72(g._stakeSharesTotal);
            globals.latestStakeId = g._latestStakeId;
            globals.claimStats = _claimStatsEncode(
                g._claimedBtcAddrCount,
                g._claimedSatoshisTotal,
                g._unclaimedSatoshisTotal
            );
        }
    }

    function _stakeLoad(StakeStore storage stRef, uint40 stakeIdParam, StakeCache memory st)
        internal
        view
    {
        /* Ensure caller's stakeIndex is still current */
        require(stakeIdParam == stRef.stakeId, "HEX: stakeIdParam not in stake");

        st._stakeId = stRef.stakeId;
        st._stakedHearts = stRef.stakedHearts;
        st._stakeShares = stRef.stakeShares;
        st._lockedDay = stRef.lockedDay;
        st._stakedDays = stRef.stakedDays;
        st._unlockedDay = stRef.unlockedDay;
        st._isAutoStake = stRef.isAutoStake;
    }

    function _stakeUpdate(StakeStore storage stRef, StakeCache memory st)
        internal
    {
        stRef.stakeId = st._stakeId;
        stRef.stakedHearts = uint72(st._stakedHearts);
        stRef.stakeShares = uint72(st._stakeShares);
        stRef.lockedDay = uint16(st._lockedDay);
        stRef.stakedDays = uint16(st._stakedDays);
        stRef.unlockedDay = uint16(st._unlockedDay);
        stRef.isAutoStake = st._isAutoStake;
    }

    function _stakeAdd(
        StakeStore[] storage stakeListRef,
        uint40 newStakeId,
        uint256 newStakedHearts,
        uint256 newStakeShares,
        uint256 newLockedDay,
        uint256 newStakedDays,
        bool newAutoStake
    )
        internal
    {
        stakeListRef.push(
            StakeStore(
                newStakeId,
                uint72(newStakedHearts),
                uint72(newStakeShares),
                uint16(newLockedDay),
                uint16(newStakedDays),
                uint16(0), // unlockedDay
                newAutoStake
            )
        );
    }

    /**
     * @dev Efficiently delete from an unordered array by moving the last element
     * to the "hole" and reducing the array length. Can change the order of the list
     * and invalidate previously held indexes.
     * @notice stakeListRef length and stakeIndex are already ensured valid in stakeEnd()
     * @param stakeListRef Reference to stakeLists[stakerAddr] array in storage
     * @param stakeIndex Index of the element to delete
     */
    function _stakeRemove(StakeStore[] storage stakeListRef, uint256 stakeIndex)
        internal
    {
        uint256 lastIndex = stakeListRef.length - 1;

        /* Skip the copy if element to be removed is already the last element */
        if (stakeIndex != lastIndex) {
            /* Copy last element to the requested element's "hole" */
            stakeListRef[stakeIndex] = stakeListRef[lastIndex];
        }

        /*
            Reduce the array length now that the array is contiguous.
            Surprisingly, 'pop()' uses less gas than 'stakeListRef.length = lastIndex'
        */
        stakeListRef.pop();
    }

    function _claimStatsEncode(
        uint256 _claimedBtcAddrCount,
        uint256 _claimedSatoshisTotal,
        uint256 _unclaimedSatoshisTotal
    )
        internal
        pure
        returns (uint128)
    {
        uint256 v = _claimedBtcAddrCount << (SATOSHI_UINT_SIZE * 2);
        v |= _claimedSatoshisTotal << SATOSHI_UINT_SIZE;
        v |= _unclaimedSatoshisTotal;

        return uint128(v);
    }

    function _claimStatsDecode(uint128 v)
        internal
        pure
        returns (uint256 _claimedBtcAddrCount, uint256 _claimedSatoshisTotal, uint256 _unclaimedSatoshisTotal)
    {
        _claimedBtcAddrCount = v >> (SATOSHI_UINT_SIZE * 2);
        _claimedSatoshisTotal = (v >> SATOSHI_UINT_SIZE) & SATOSHI_UINT_MASK;
        _unclaimedSatoshisTotal = v & SATOSHI_UINT_MASK;

        return (_claimedBtcAddrCount, _claimedSatoshisTotal, _unclaimedSatoshisTotal);
    }

    /**
     * @dev Estimate the stake payout for an incomplete day
     * @param g Cache of stored globals
     * @param stakeSharesParam Param from stake to calculate bonuses for
     * @param day Day to calculate bonuses for
     * @return Payout in Hearts
     */
    function _estimatePayoutRewardsDay(GlobalsCache memory g, uint256 stakeSharesParam, uint256 day)
        internal
        view
        returns (uint256 payout)
    {
        /* Prevent updating state for this estimation */
        GlobalsCache memory gTmp;
        _globalsCacheSnapshot(g, gTmp);

        DailyRoundState memory rs;
        rs._allocSupplyCached = totalSupply() + g._lockedHeartsTotal;

        _dailyRoundCalc(gTmp, rs, day);

        /* Stake is no longer locked so it must be added to total as if it were */
        gTmp._stakeSharesTotal += stakeSharesParam;

        payout = rs._payoutTotal * stakeSharesParam / gTmp._stakeSharesTotal;

        if (day == BIG_PAY_DAY) {
            uint256 bigPaySlice = gTmp._unclaimedSatoshisTotal * HEARTS_PER_SATOSHI * stakeSharesParam
                / gTmp._stakeSharesTotal;
            payout += bigPaySlice + _calcAdoptionBonus(gTmp, bigPaySlice);
        }

        return payout;
    }

    function _calcAdoptionBonus(GlobalsCache memory g, uint256 payout)
        internal
        pure
        returns (uint256)
    {
        /*
            VIRAL REWARDS: Add adoption percentage bonus to payout

            viral = payout * (claimedBtcAddrCount / CLAIMABLE_BTC_ADDR_COUNT)
        */
        uint256 viral = payout * g._claimedBtcAddrCount / CLAIMABLE_BTC_ADDR_COUNT;

        /*
            CRIT MASS REWARDS: Add adoption percentage bonus to payout

            crit  = payout * (claimedSatoshisTotal / CLAIMABLE_SATOSHIS_TOTAL)
        */
        uint256 crit = payout * g._claimedSatoshisTotal / CLAIMABLE_SATOSHIS_TOTAL;

        return viral + crit;
    }

    function _dailyRoundCalc(GlobalsCache memory g, DailyRoundState memory rs, uint256 day)
        private
        pure
    {
        /*
            Calculate payout round

            Inflation of 3.69% inflation per 364 days             (approx 1 year)
            dailyInterestRate   = exp(log(1 + 3.69%)  / 364) - 1
                                = exp(log(1 + 0.0369) / 364) - 1
                                = exp(log(1.0369) / 364) - 1
                                = 0.000099553011616349            (approx)

            payout  = allocSupply * dailyInterestRate
                    = allocSupply / (1 / dailyInterestRate)
                    = allocSupply / (1 / 0.000099553011616349)
                    = allocSupply / 10044.899534066692            (approx)
                    = allocSupply * 10000 / 100448995             (* 10000/10000 for int precision)
        */
        rs._payoutTotal = rs._allocSupplyCached * 10000 / 100448995;

        if (day < CLAIM_PHASE_END_DAY) {
            uint256 bigPaySlice = g._unclaimedSatoshisTotal * HEARTS_PER_SATOSHI / CLAIM_PHASE_DAYS;

            uint256 originBonus = bigPaySlice + _calcAdoptionBonus(g, rs._payoutTotal + bigPaySlice);
            rs._mintOriginBatch += originBonus;
            rs._allocSupplyCached += originBonus;

            rs._payoutTotal += _calcAdoptionBonus(g, rs._payoutTotal);
        }

        if (g._stakePenaltyTotal != 0) {
            rs._payoutTotal += g._stakePenaltyTotal;
            g._stakePenaltyTotal = 0;
        }
    }

    function _dailyRoundCalcAndStore(GlobalsCache memory g, DailyRoundState memory rs, uint256 day)
        private
    {
        _dailyRoundCalc(g, rs, day);

        dailyData[day].dayPayoutTotal = uint72(rs._payoutTotal);
        dailyData[day].dayStakeSharesTotal = uint72(g._stakeSharesTotal);
        dailyData[day].dayUnclaimedSatoshisTotal = uint56(g._unclaimedSatoshisTotal);
    }

    function _dailyDataUpdate(GlobalsCache memory g, uint256 beforeDay, bool isAutoUpdate)
        private
    {
        if (g._dailyDataCount >= beforeDay) {
            /* Already up-to-date */
            return;
        }

        DailyRoundState memory rs;
        rs._allocSupplyCached = totalSupply() + g._lockedHeartsTotal;

        uint256 day = g._dailyDataCount;

        _dailyRoundCalcAndStore(g, rs, day);

        /* Stakes started during this day are added to the total the next day */
        if (g._nextStakeSharesTotal != 0) {
            g._stakeSharesTotal += g._nextStakeSharesTotal;
            g._nextStakeSharesTotal = 0;
        }

        while (++day < beforeDay) {
            _dailyRoundCalcAndStore(g, rs, day);
        }

        _emitDailyDataUpdate(g._dailyDataCount, day, isAutoUpdate);
        g._dailyDataCount = day;

        if (rs._mintOriginBatch != 0) {
            _mint(ORIGIN_ADDR, rs._mintOriginBatch);
        }
    }

    function _emitDailyDataUpdate(uint256 beginDay, uint256 endDay, bool isAutoUpdate)
        private
    {
        emit DailyDataUpdate( // (auto-generated event)
            uint256(uint40(block.timestamp))
                | (uint256(uint16(beginDay)) << 40)
                | (uint256(uint16(endDay)) << 56)
                | (isAutoUpdate ? (1 << 72) : 0),
            msg.sender
        );
    }
}

contract StakeableToken is GlobalsAndUtility {
    /**
     * @dev PUBLIC FACING: Open a stake.
     * @param newStakedHearts Number of Hearts to stake
     * @param newStakedDays Number of days to stake
     */
    function stakeStart(uint256 newStakedHearts, uint256 newStakedDays)
        external
    {
        GlobalsCache memory g;
        GlobalsCache memory gSnapshot;
        _globalsLoad(g, gSnapshot);

        /* Enforce the minimum stake time */
        require(newStakedDays >= MIN_STAKE_DAYS, "HEX: newStakedDays lower than minimum");

        /* Check if log data needs to be updated */
        _dailyDataUpdateAuto(g);

        _stakeStart(g, newStakedHearts, newStakedDays, false);

        /* Remove staked Hearts from balance of staker */
        _burn(msg.sender, newStakedHearts);

        _globalsSync(g, gSnapshot);
    }

    /**
     * @dev PUBLIC FACING: Unlocks a completed stake, distributing the proceeds of any penalty
     * immediately. The staker must still call stakeEnd() to retrieve their stake return (if any).
     * @param stakerAddr Address of staker
     * @param stakeIndex Index of stake within stake list
     * @param stakeIdParam The stake's id
     */
    function stakeGoodAccounting(address stakerAddr, uint256 stakeIndex, uint40 stakeIdParam)
        external
    {
        GlobalsCache memory g;
        GlobalsCache memory gSnapshot;
        _globalsLoad(g, gSnapshot);

        /* require() is more informative than the default assert() */
        require(stakeLists[stakerAddr].length != 0, "HEX: Empty stake list");
        require(stakeIndex < stakeLists[stakerAddr].length, "HEX: stakeIndex invalid");

        StakeStore storage stRef = stakeLists[stakerAddr][stakeIndex];

        /* Get stake copy */
        StakeCache memory st;
        _stakeLoad(stRef, stakeIdParam, st);

        /* Stake must have served full term */
        require(g._currentDay >= st._lockedDay + st._stakedDays, "HEX: Stake not fully served");

        /* Stake must still be locked */
        require(st._unlockedDay == 0, "HEX: Stake already unlocked");

        /* Check if log data needs to be updated */
        _dailyDataUpdateAuto(g);

        /* Unlock the completed stake */
        _stakeUnlock(g, st);

        /* stakeReturn value is unused here */
        (, uint256 payout, uint256 penalty, uint256 cappedPenalty) = _stakePerformance(
            g,
            st,
            st._stakedDays
        );

        _emitStakeGoodAccounting(
            stakerAddr,
            stakeIdParam,
            st._stakedHearts,
            st._stakeShares,
            payout,
            penalty
        );

        if (cappedPenalty != 0) {
            _splitPenaltyProceeds(g, cappedPenalty);
        }

        /* st._unlockedDay has changed */
        _stakeUpdate(stRef, st);

        _globalsSync(g, gSnapshot);
    }

    /**
     * @dev PUBLIC FACING: Closes a stake. The order of the stake list can change so
     * a stake id is used to reject stale indexes.
     * @param stakeIndex Index of stake within stake list
     * @param stakeIdParam The stake's id
     */
    function stakeEnd(uint256 stakeIndex, uint40 stakeIdParam)
        external
    {
        GlobalsCache memory g;
        GlobalsCache memory gSnapshot;
        _globalsLoad(g, gSnapshot);

        StakeStore[] storage stakeListRef = stakeLists[msg.sender];

        /* require() is more informative than the default assert() */
        require(stakeListRef.length != 0, "HEX: Empty stake list");
        require(stakeIndex < stakeListRef.length, "HEX: stakeIndex invalid");

        /* Get stake copy */
        StakeCache memory st;
        _stakeLoad(stakeListRef[stakeIndex], stakeIdParam, st);

        /* Check if log data needs to be updated */
        _dailyDataUpdateAuto(g);

        uint256 servedDays = 0;

        bool prevUnlocked = (st._unlockedDay != 0);
        uint256 stakeReturn;
        uint256 payout = 0;
        uint256 penalty = 0;
        uint256 cappedPenalty = 0;

        if (g._currentDay >= st._lockedDay) {
            if (prevUnlocked) {
                /* Previously unlocked in stakeGoodAccounting(), so must have served full term */
                servedDays = st._stakedDays;
            } else {
                _stakeUnlock(g, st);

                servedDays = g._currentDay - st._lockedDay;
                if (servedDays > st._stakedDays) {
                    servedDays = st._stakedDays;
                } else {
                    /* Deny early-unstake before an auto-stake minimum has been served */
                    if (servedDays < MIN_AUTO_STAKE_DAYS) {
                        require(!st._isAutoStake, "HEX: Auto-stake still locked");
                    }
                }
            }

            (stakeReturn, payout, penalty, cappedPenalty) = _stakePerformance(g, st, servedDays);
        } else {
            /* Deny early-unstake before an auto-stake minimum has been served */
            require(!st._isAutoStake, "HEX: Auto-stake still locked");

            /* Stake hasn't been added to the total yet, so no penalties or rewards apply */
            g._nextStakeSharesTotal -= st._stakeShares;

            stakeReturn = st._stakedHearts;
        }

        _emitStakeEnd(
            stakeIdParam,
            st._stakedHearts,
            st._stakeShares,
            payout,
            penalty,
            servedDays,
            prevUnlocked
        );

        if (cappedPenalty != 0 && !prevUnlocked) {
            /* Split penalty proceeds only if not previously unlocked by stakeGoodAccounting() */
            _splitPenaltyProceeds(g, cappedPenalty);
        }

        /* Pay the stake return, if any, to the staker */
        if (stakeReturn != 0) {
            _mint(msg.sender, stakeReturn);

            /* Update the share rate if necessary */
            _shareRateUpdate(g, st, stakeReturn);
        }
        g._lockedHeartsTotal -= st._stakedHearts;

        _stakeRemove(stakeListRef, stakeIndex);

        _globalsSync(g, gSnapshot);
    }

    /**
     * @dev PUBLIC FACING: Return the current stake count for a staker address
     * @param stakerAddr Address of staker
     */
    function stakeCount(address stakerAddr)
        external
        view
        returns (uint256)
    {
        return stakeLists[stakerAddr].length;
    }

    /**
     * @dev Open a stake.
     * @param g Cache of stored globals
     * @param newStakedHearts Number of Hearts to stake
     * @param newStakedDays Number of days to stake
     * @param newAutoStake Stake is automatic directly from a new claim
     */
    function _stakeStart(
        GlobalsCache memory g,
        uint256 newStakedHearts,
        uint256 newStakedDays,
        bool newAutoStake
    )
        internal
    {
        /* Enforce the maximum stake time */
        require(newStakedDays <= MAX_STAKE_DAYS, "HEX: newStakedDays higher than maximum");

        uint256 bonusHearts = _stakeStartBonusHearts(newStakedHearts, newStakedDays);
        uint256 newStakeShares = (newStakedHearts + bonusHearts) * SHARE_RATE_SCALE / g._shareRate;

        /* Ensure newStakedHearts is enough for at least one stake share */
        require(newStakeShares != 0, "HEX: newStakedHearts must be at least minimum shareRate");

        /*
            The stakeStart timestamp will always be part-way through the current
            day, so it needs to be rounded-up to the next day to ensure all
            stakes align with the same fixed calendar days. The current day is
            already rounded-down, so rounded-up is current day + 1.
        */
        uint256 newLockedDay = g._currentDay < CLAIM_PHASE_START_DAY
            ? CLAIM_PHASE_START_DAY + 1
            : g._currentDay + 1;

        /* Create Stake */
        uint40 newStakeId = ++g._latestStakeId;
        _stakeAdd(
            stakeLists[msg.sender],
            newStakeId,
            newStakedHearts,
            newStakeShares,
            newLockedDay,
            newStakedDays,
            newAutoStake
        );

        _emitStakeStart(newStakeId, newStakedHearts, newStakeShares, newStakedDays, newAutoStake);

        /* Stake is added to total in the next round, not the current round */
        g._nextStakeSharesTotal += newStakeShares;

        /* Track total staked Hearts for inflation calculations */
        g._lockedHeartsTotal += newStakedHearts;
    }

    /**
     * @dev Calculates total stake payout including rewards for a multi-day range
     * @param g Cache of stored globals
     * @param stakeSharesParam Param from stake to calculate bonuses for
     * @param beginDay First day to calculate bonuses for
     * @param endDay Last day (non-inclusive) of range to calculate bonuses for
     * @return Payout in Hearts
     */
    function _calcPayoutRewards(
        GlobalsCache memory g,
        uint256 stakeSharesParam,
        uint256 beginDay,
        uint256 endDay
    )
        private
        view
        returns (uint256 payout)
    {
        for (uint256 day = beginDay; day < endDay; day++) {
            payout += dailyData[day].dayPayoutTotal * stakeSharesParam
                / dailyData[day].dayStakeSharesTotal;
        }

        /* Less expensive to re-read storage than to have the condition inside the loop */
        if (beginDay <= BIG_PAY_DAY && endDay > BIG_PAY_DAY) {
            uint256 bigPaySlice = g._unclaimedSatoshisTotal * HEARTS_PER_SATOSHI * stakeSharesParam
                / dailyData[BIG_PAY_DAY].dayStakeSharesTotal;

            payout += bigPaySlice + _calcAdoptionBonus(g, bigPaySlice);
        }
        return payout;
    }

    /**
     * @dev Calculate bonus Hearts for a new stake, if any
     * @param newStakedHearts Number of Hearts to stake
     * @param newStakedDays Number of days to stake
     */
    function _stakeStartBonusHearts(uint256 newStakedHearts, uint256 newStakedDays)
        private
        pure
        returns (uint256 bonusHearts)
    {
        /*
            LONGER PAYS BETTER:

            If longer than 1 day stake is committed to, each extra day
            gives bonus shares of approximately 0.0548%, which is approximately 20%
            extra per year of increased stake length committed to, but capped to a
            maximum of 200% extra.

            extraDays       =  stakedDays - 1

            longerBonus%    = (extraDays / 364) * 20%
                            = (extraDays / 364) / 5
                            =  extraDays / 1820
                            =  extraDays / LPB

            extraDays       =  longerBonus% * 1820
            extraDaysMax    =  longerBonusMax% * 1820
                            =  200% * 1820
                            =  3640
                            =  LPB_MAX_DAYS

            BIGGER PAYS BETTER:

            Bonus percentage scaled 0% to 10% for the first 150M HEX of stake.

            biggerBonus%    = (cappedHearts /  BPB_MAX_HEARTS) * 10%
                            = (cappedHearts /  BPB_MAX_HEARTS) / 10
                            =  cappedHearts / (BPB_MAX_HEARTS * 10)
                            =  cappedHearts /  BPB

            COMBINED:

            combinedBonus%  =            longerBonus%  +  biggerBonus%

                                      cappedExtraDays     cappedHearts
                            =         ---------------  +  ------------
                                            LPB               BPB

                                cappedExtraDays * BPB     cappedHearts * LPB
                            =   ---------------------  +  ------------------
                                      LPB * BPB               LPB * BPB

                                cappedExtraDays * BPB  +  cappedHearts * LPB
                            =   --------------------------------------------
                                                  LPB  *  BPB

            bonusHearts     = hearts * combinedBonus%
                            = hearts * (cappedExtraDays * BPB  +  cappedHearts * LPB) / (LPB * BPB)
        */
        uint256 cappedExtraDays = 0;

        /* Must be more than 1 day for Longer-Pays-Better */
        if (newStakedDays > 1) {
            cappedExtraDays = newStakedDays <= LPB_MAX_DAYS ? newStakedDays - 1 : LPB_MAX_DAYS;
        }

        uint256 cappedStakedHearts = newStakedHearts <= BPB_MAX_HEARTS
            ? newStakedHearts
            : BPB_MAX_HEARTS;

        bonusHearts = cappedExtraDays * BPB + cappedStakedHearts * LPB;
        bonusHearts = newStakedHearts * bonusHearts / (LPB * BPB);

        return bonusHearts;
    }

    function _stakeUnlock(GlobalsCache memory g, StakeCache memory st)
        private
        pure
    {
        g._stakeSharesTotal -= st._stakeShares;
        st._unlockedDay = g._currentDay;
    }

    function _stakePerformance(GlobalsCache memory g, StakeCache memory st, uint256 servedDays)
        private
        view
        returns (uint256 stakeReturn, uint256 payout, uint256 penalty, uint256 cappedPenalty)
    {
        if (servedDays < st._stakedDays) {
            (payout, penalty) = _calcPayoutAndEarlyPenalty(
                g,
                st._lockedDay,
                st._stakedDays,
                servedDays,
                st._stakeShares
            );
            stakeReturn = st._stakedHearts + payout;
        } else {
            // servedDays must == stakedDays here
            payout = _calcPayoutRewards(
                g,
                st._stakeShares,
                st._lockedDay,
                st._lockedDay + servedDays
            );
            stakeReturn = st._stakedHearts + payout;

            penalty = _calcLatePenalty(st._lockedDay, st._stakedDays, st._unlockedDay, stakeReturn);
        }
        if (penalty != 0) {
            if (penalty > stakeReturn) {
                /* Cannot have a negative stake return */
                cappedPenalty = stakeReturn;
                stakeReturn = 0;
            } else {
                /* Remove penalty from the stake return */
                cappedPenalty = penalty;
                stakeReturn -= cappedPenalty;
            }
        }
        return (stakeReturn, payout, penalty, cappedPenalty);
    }

    function _calcPayoutAndEarlyPenalty(
        GlobalsCache memory g,
        uint256 lockedDayParam,
        uint256 stakedDaysParam,
        uint256 servedDays,
        uint256 stakeSharesParam
    )
        private
        view
        returns (uint256 payout, uint256 penalty)
    {
        uint256 servedEndDay = lockedDayParam + servedDays;

        /* 50% of stakedDays (rounded up) with a minimum applied */
        uint256 penaltyDays = (stakedDaysParam + 1) / 2;
        if (penaltyDays < EARLY_PENALTY_MIN_DAYS) {
            penaltyDays = EARLY_PENALTY_MIN_DAYS;
        }

        if (servedDays == 0) {
            /* Fill penalty days with the estimated average payout */
            uint256 expected = _estimatePayoutRewardsDay(g, stakeSharesParam, lockedDayParam);
            penalty = expected * penaltyDays;
            return (payout, penalty); // Actual payout was 0
        }

        if (penaltyDays < servedDays) {
            /*
                Simplified explanation of intervals where end-day is non-inclusive:

                penalty:    [lockedDay  ...  penaltyEndDay)
                delta:                      [penaltyEndDay  ...  servedEndDay)
                payout:     [lockedDay  .......................  servedEndDay)
            */
            uint256 penaltyEndDay = lockedDayParam + penaltyDays;
            penalty = _calcPayoutRewards(g, stakeSharesParam, lockedDayParam, penaltyEndDay);

            uint256 delta = _calcPayoutRewards(g, stakeSharesParam, penaltyEndDay, servedEndDay);
            payout = penalty + delta;
            return (payout, penalty);
        }

        /* penaltyDays >= servedDays  */
        payout = _calcPayoutRewards(g, stakeSharesParam, lockedDayParam, servedEndDay);

        if (penaltyDays == servedDays) {
            penalty = payout;
        } else {
            /*
                (penaltyDays > servedDays) means not enough days served, so fill the
                penalty days with the average payout from only the days that were served.
            */
            penalty = payout * penaltyDays / servedDays;
        }
        return (payout, penalty);
    }

    function _calcLatePenalty(
        uint256 lockedDayParam,
        uint256 stakedDaysParam,
        uint256 unlockedDayParam,
        uint256 rawStakeReturn
    )
        private
        pure
        returns (uint256)
    {
        /* Allow grace time before penalties accrue */
        uint256 maxUnlockedDay = lockedDayParam + stakedDaysParam + LATE_PENALTY_GRACE_DAYS;
        if (unlockedDayParam <= maxUnlockedDay) {
            return 0;
        }

        /* Calculate penalty as a percentage of stake return based on time */
        return rawStakeReturn * (unlockedDayParam - maxUnlockedDay) / LATE_PENALTY_SCALE_DAYS;
    }

    function _splitPenaltyProceeds(GlobalsCache memory g, uint256 penalty)
        private
    {
        /* Split a penalty 50:50 between Origin and stakePenaltyTotal */
        uint256 splitPenalty = penalty / 2;

        if (splitPenalty != 0) {
            _mint(ORIGIN_ADDR, splitPenalty);
        }

        /* Use the other half of the penalty to account for an odd-numbered penalty */
        splitPenalty = penalty - splitPenalty;
        g._stakePenaltyTotal += splitPenalty;
    }

    function _shareRateUpdate(GlobalsCache memory g, StakeCache memory st, uint256 stakeReturn)
        private
    {
        if (stakeReturn > st._stakedHearts) {
            /*
                Calculate the new shareRate that would yield the same number of shares if
                the user re-staked this stakeReturn, factoring in any bonuses they would
                receive in stakeStart().
            */
            uint256 bonusHearts = _stakeStartBonusHearts(stakeReturn, st._stakedDays);
            uint256 newShareRate = (stakeReturn + bonusHearts) * SHARE_RATE_SCALE / st._stakeShares;

            if (newShareRate > SHARE_RATE_MAX) {
                /*
                    Realistically this can't happen, but there are contrived theoretical
                    scenarios that can lead to extreme values of newShareRate, so it is
                    capped to prevent them anyway.
                */
                newShareRate = SHARE_RATE_MAX;
            }

            if (newShareRate > g._shareRate) {
                g._shareRate = newShareRate;

                _emitShareRateChange(newShareRate, st._stakeId);
            }
        }
    }

    function _emitStakeStart(
        uint40 stakeId,
        uint256 stakedHearts,
        uint256 stakeShares,
        uint256 stakedDays,
        bool isAutoStake
    )
        private
    {
        emit StakeStart( // (auto-generated event)
            uint256(uint40(block.timestamp))
                | (uint256(uint72(stakedHearts)) << 40)
                | (uint256(uint72(stakeShares)) << 112)
                | (uint256(uint16(stakedDays)) << 184)
                | (isAutoStake ? (1 << 200) : 0),
            msg.sender,
            stakeId
        );
    }

    function _emitStakeGoodAccounting(
        address stakerAddr,
        uint40 stakeId,
        uint256 stakedHearts,
        uint256 stakeShares,
        uint256 payout,
        uint256 penalty
    )
        private
    {
        emit StakeGoodAccounting( // (auto-generated event)
            uint256(uint40(block.timestamp))
                | (uint256(uint72(stakedHearts)) << 40)
                | (uint256(uint72(stakeShares)) << 112)
                | (uint256(uint72(payout)) << 184),
            uint256(uint72(penalty)),
            stakerAddr,
            stakeId,
            msg.sender
        );
    }

    function _emitStakeEnd(
        uint40 stakeId,
        uint256 stakedHearts,
        uint256 stakeShares,
        uint256 payout,
        uint256 penalty,
        uint256 servedDays,
        bool prevUnlocked
    )
        private
    {
        emit StakeEnd( // (auto-generated event)
            uint256(uint40(block.timestamp))
                | (uint256(uint72(stakedHearts)) << 40)
                | (uint256(uint72(stakeShares)) << 112)
                | (uint256(uint72(payout)) << 184),
            uint256(uint72(penalty))
                | (uint256(uint16(servedDays)) << 72)
                | (prevUnlocked ? (1 << 88) : 0),
            msg.sender,
            stakeId
        );
    }

    function _emitShareRateChange(uint256 shareRate, uint40 stakeId)
        private
    {
        emit ShareRateChange( // (auto-generated event)
            uint256(uint40(block.timestamp))
                | (uint256(uint40(shareRate)) << 40),
            stakeId
        );
    }
}

/**
 * @dev These functions deal with verification of Merkle trees (hash trees),
 */
library MerkleProof {
    /**
     * @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
     * defined by `root`. For this, a `proof` must be provided, containing
     * sibling hashes on the branch from the leaf to the root of the tree. Each
     * pair of leaves and each pair of pre-images are assumed to be sorted.
     */
    function verify(bytes32[] memory proof, bytes32 root, bytes32 leaf) internal pure returns (bool) {
        bytes32 computedHash = leaf;

        for (uint256 i = 0; i < proof.length; i++) {
            bytes32 proofElement = proof[i];

            if (computedHash < proofElement) {
                // Hash(current computed hash + current element of the proof)
                computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
            } else {
                // Hash(current element of the proof + current computed hash)
                computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
            }
        }

        // Check if the computed hash (root) is equal to the provided root
        return computedHash == root;
    }
}

contract UTXOClaimValidation is StakeableToken {
    /**
     * @dev PUBLIC FACING: Verify a BTC address and balance are unclaimed and part of the Merkle tree
     * @param btcAddr Bitcoin address (binary; no base58-check encoding)
     * @param rawSatoshis Raw BTC address balance in Satoshis
     * @param proof Merkle tree proof
     * @return True if can be claimed
     */
    function btcAddressIsClaimable(bytes20 btcAddr, uint256 rawSatoshis, bytes32[] calldata proof)
        external
        view
        returns (bool)
    {
        uint256 day = _currentDay();

        require(day >= CLAIM_PHASE_START_DAY, "HEX: Claim phase has not yet started");
        require(day < CLAIM_PHASE_END_DAY, "HEX: Claim phase has ended");

        /* Don't need to check Merkle proof if UTXO BTC address has already been claimed    */
        if (btcAddressClaims[btcAddr]) {
            return false;
        }

        /* Verify the Merkle tree proof */
        return _btcAddressIsValid(btcAddr, rawSatoshis, proof);
    }

    /**
     * @dev PUBLIC FACING: Verify a BTC address and balance are part of the Merkle tree
     * @param btcAddr Bitcoin address (binary; no base58-check encoding)
     * @param rawSatoshis Raw BTC address balance in Satoshis
     * @param proof Merkle tree proof
     * @return True if valid
     */
    function btcAddressIsValid(bytes20 btcAddr, uint256 rawSatoshis, bytes32[] calldata proof)
        external
        pure
        returns (bool)
    {
        return _btcAddressIsValid(btcAddr, rawSatoshis, proof);
    }

    /**
     * @dev PUBLIC FACING: Verify a Merkle proof using the UTXO Merkle tree
     * @param merkleLeaf Leaf asserted to be present in the Merkle tree
     * @param proof Generated Merkle tree proof
     * @return True if valid
     */
    function merkleProofIsValid(bytes32 merkleLeaf, bytes32[] calldata proof)
        external
        pure
        returns (bool)
    {
        return _merkleProofIsValid(merkleLeaf, proof);
    }

    /**
     * @dev PUBLIC FACING: Verify that a Bitcoin signature matches the claim message containing
     * the Ethereum address and claim param hash
     * @param claimToAddr Eth address within the signed claim message
     * @param claimParamHash Param hash within the signed claim message
     * @param pubKeyX First  half of uncompressed ECDSA public key
     * @param pubKeyY Second half of uncompressed ECDSA public key
     * @param claimFlags Claim flags specifying address and message formats
     * @param v v parameter of ECDSA signature
     * @param r r parameter of ECDSA signature
     * @param s s parameter of ECDSA signature
     * @return True if matching
     */
    function claimMessageMatchesSignature(
        address claimToAddr,
        bytes32 claimParamHash,
        bytes32 pubKeyX,
        bytes32 pubKeyY,
        uint8 claimFlags,
        uint8 v,
        bytes32 r,
        bytes32 s
    )
        public
        pure
        returns (bool)
    {
        require(v >= 27 && v <= 30, "HEX: v invalid");

        /*
            ecrecover() returns an Eth address rather than a public key, so
            we must do the same to compare.
        */
        address pubKeyEthAddr = pubKeyToEthAddress(pubKeyX, pubKeyY);

        /* Create and hash the claim message text */
        bytes32 messageHash = _hash256(
            _claimMessageCreate(claimToAddr, claimParamHash, claimFlags)
        );

        /* Verify the public key */
        return ecrecover(messageHash, v, r, s) == pubKeyEthAddr;
    }

    /**
     * @dev PUBLIC FACING: Derive an Ethereum address from an ECDSA public key
     * @param pubKeyX First  half of uncompressed ECDSA public key
     * @param pubKeyY Second half of uncompressed ECDSA public key
     * @return Derived Eth address
     */
    function pubKeyToEthAddress(bytes32 pubKeyX, bytes32 pubKeyY)
        public
        pure
        returns (address)
    {
        return address(uint160(uint256(keccak256(abi.encodePacked(pubKeyX, pubKeyY)))));
    }

    /**
     * @dev PUBLIC FACING: Derive a Bitcoin address from an ECDSA public key
     * @param pubKeyX First  half of uncompressed ECDSA public key
     * @param pubKeyY Second half of uncompressed ECDSA public key
     * @param claimFlags Claim flags specifying address and message formats
     * @return Derived Bitcoin address (binary; no base58-check encoding)
     */
    function pubKeyToBtcAddress(bytes32 pubKeyX, bytes32 pubKeyY, uint8 claimFlags)
        public
        pure
        returns (bytes20)
    {
        /*
            Helpful references:
             - https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses
             - https://github.com/cryptocoinjs/ecurve/blob/master/lib/point.js
        */
        uint8 startingByte;
        bytes memory pubKey;
        bool compressed = (claimFlags & CLAIM_FLAG_BTC_ADDR_COMPRESSED) != 0;
        bool nested = (claimFlags & CLAIM_FLAG_BTC_ADDR_P2WPKH_IN_P2SH) != 0;
        bool bech32 = (claimFlags & CLAIM_FLAG_BTC_ADDR_BECH32) != 0;

        if (compressed) {
            /* Compressed public key format */
            require(!(nested && bech32), "HEX: claimFlags invalid");

            startingByte = (pubKeyY[31] & 0x01) == 0 ? 0x02 : 0x03;
            pubKey = abi.encodePacked(startingByte, pubKeyX);
        } else {
            /* Uncompressed public key format */
            require(!nested && !bech32, "HEX: claimFlags invalid");

            startingByte = 0x04;
            pubKey = abi.encodePacked(startingByte, pubKeyX, pubKeyY);
        }

        bytes20 pubKeyHash = _hash160(pubKey);
        if (nested) {
            return _hash160(abi.encodePacked(hex"0014", pubKeyHash));
        }
        return pubKeyHash;
    }

    /**
     * @dev Verify a BTC address and balance are part of the Merkle tree
     * @param btcAddr Bitcoin address (binary; no base58-check encoding)
     * @param rawSatoshis Raw BTC address balance in Satoshis
     * @param proof Merkle tree proof
     * @return True if valid
     */
    function _btcAddressIsValid(bytes20 btcAddr, uint256 rawSatoshis, bytes32[] memory proof)
        internal
        pure
        returns (bool)
    {
        /*
            Ensure the proof does not attempt to treat a Merkle leaf as if it were an
            internal Merkle tree node. A leaf will always have the zero-fill. An
            internal node will never have the zero-fill, as guaranteed by HEX's Merkle
            tree construction.

            The first element, proof[0], will always be a leaf because it is the pair
            of the leaf being validated. The rest of the elements, proof[1..length-1],
            must be internal nodes.

            The number of leaves (CLAIMABLE_BTC_ADDR_COUNT) is even, as guaranteed by
            HEX's Merkle tree construction, which eliminates the only edge-case where
            this validation would not apply.
        */
        require((uint256(proof[0]) & MERKLE_LEAF_FILL_MASK) == 0, "HEX: proof invalid");
        for (uint256 i = 1; i < proof.length; i++) {
            require((uint256(proof[i]) & MERKLE_LEAF_FILL_MASK) != 0, "HEX: proof invalid");
        }

        /*
            Calculate the 32 byte Merkle leaf associated with this BTC address and balance
                160 bits: BTC address
                 52 bits: Zero-fill
                 45 bits: Satoshis (limited by MAX_BTC_ADDR_BALANCE_SATOSHIS)
        */
        bytes32 merkleLeaf = bytes32(btcAddr) | bytes32(rawSatoshis);

        /* Verify the Merkle tree proof */
        return _merkleProofIsValid(merkleLeaf, proof);
    }

    /**
     * @dev Verify a Merkle proof using the UTXO Merkle tree
     * @param merkleLeaf Leaf asserted to be present in the Merkle tree
     * @param proof Generated Merkle tree proof
     * @return True if valid
     */
    function _merkleProofIsValid(bytes32 merkleLeaf, bytes32[] memory proof)
        private
        pure
        returns (bool)
    {
        return MerkleProof.verify(proof, MERKLE_TREE_ROOT, merkleLeaf);
    }

    function _claimMessageCreate(address claimToAddr, bytes32 claimParamHash, uint8 claimFlags)
        private
        pure
        returns (bytes memory)
    {
        bytes memory prefixStr = (claimFlags & CLAIM_FLAG_MSG_PREFIX_OLD) != 0
            ? OLD_CLAIM_PREFIX_STR
            : STD_CLAIM_PREFIX_STR;

        bool includeAddrChecksum = (claimFlags & CLAIM_FLAG_ETH_ADDR_LOWERCASE) == 0;

        bytes memory addrStr = _addressStringCreate(claimToAddr, includeAddrChecksum);

        if (claimParamHash == 0) {
            return abi.encodePacked(
                BITCOIN_SIG_PREFIX_LEN,
                BITCOIN_SIG_PREFIX_STR,
                uint8(prefixStr.length) + ETH_ADDRESS_HEX_LEN,
                prefixStr,
                addrStr
            );
        }

        bytes memory claimParamHashStr = new bytes(CLAIM_PARAM_HASH_HEX_LEN);

        _hexStringFromData(claimParamHashStr, claimParamHash, CLAIM_PARAM_HASH_BYTE_LEN);

        return abi.encodePacked(
            BITCOIN_SIG_PREFIX_LEN,
            BITCOIN_SIG_PREFIX_STR,
            uint8(prefixStr.length) + ETH_ADDRESS_HEX_LEN + 1 + CLAIM_PARAM_HASH_HEX_LEN,
            prefixStr,
            addrStr,
            "_",
            claimParamHashStr
        );
    }

    function _addressStringCreate(address addr, bool includeAddrChecksum)
        private
        pure
        returns (bytes memory addrStr)
    {
        addrStr = new bytes(ETH_ADDRESS_HEX_LEN);
        _hexStringFromData(addrStr, bytes32(bytes20(addr)), ETH_ADDRESS_BYTE_LEN);

        if (includeAddrChecksum) {
            bytes32 addrStrHash = keccak256(addrStr);

            uint256 offset = 0;

            for (uint256 i = 0; i < ETH_ADDRESS_BYTE_LEN; i++) {
                uint8 b = uint8(addrStrHash[i]);

                _addressStringChecksumChar(addrStr, offset++, b >> 4);
                _addressStringChecksumChar(addrStr, offset++, b & 0x0f);
            }
        }

        return addrStr;
    }

    function _addressStringChecksumChar(bytes memory addrStr, uint256 offset, uint8 hashNybble)
        private
        pure
    {
        bytes1 ch = addrStr[offset];

        if (ch >= "a" && hashNybble >= 8) {
            addrStr[offset] = ch ^ 0x20;
        }
    }

    function _hexStringFromData(bytes memory hexStr, bytes32 data, uint256 dataLen)
        private
        pure
    {
        uint256 offset = 0;

        for (uint256 i = 0; i < dataLen; i++) {
            uint8 b = uint8(data[i]);

            hexStr[offset++] = HEX_DIGITS[b >> 4];
            hexStr[offset++] = HEX_DIGITS[b & 0x0f];
        }
    }

    /**
     * @dev sha256(sha256(data))
     * @param data Data to be hashed
     * @return 32-byte hash
     */
    function _hash256(bytes memory data)
        private
        pure
        returns (bytes32)
    {
        return sha256(abi.encodePacked(sha256(data)));
    }

    /**
     * @dev ripemd160(sha256(data))
     * @param data Data to be hashed
     * @return 20-byte hash
     */
    function _hash160(bytes memory data)
        private
        pure
        returns (bytes20)
    {
        return ripemd160(abi.encodePacked(sha256(data)));
    }
}

contract UTXORedeemableToken is UTXOClaimValidation {
    /**
     * @dev PUBLIC FACING: Claim a BTC address and its Satoshi balance in Hearts
     * crediting the appropriate amount to a specified Eth address. Bitcoin ECDSA
     * signature must be from that BTC address and must match the claim message
     * for the Eth address.
     * @param rawSatoshis Raw BTC address balance in Satoshis
     * @param proof Merkle tree proof
     * @param claimToAddr Destination Eth address to credit Hearts to
     * @param pubKeyX First  half of uncompressed ECDSA public key for the BTC address
     * @param pubKeyY Second half of uncompressed ECDSA public key for the BTC address
     * @param claimFlags Claim flags specifying address and message formats
     * @param v v parameter of ECDSA signature
     * @param r r parameter of ECDSA signature
     * @param s s parameter of ECDSA signature
     * @param autoStakeDays Number of days to auto-stake, subject to minimum auto-stake days
     * @param referrerAddr Eth address of referring user (optional; 0x0 for no referrer)
     * @return Total number of Hearts credited, if successful
     */
    function btcAddressClaim(
        uint256 rawSatoshis,
        bytes32[] calldata proof,
        address claimToAddr,
        bytes32 pubKeyX,
        bytes32 pubKeyY,
        uint8 claimFlags,
        uint8 v,
        bytes32 r,
        bytes32 s,
        uint256 autoStakeDays,
        address referrerAddr
    )
        external
        returns (uint256)
    {
        /* Sanity check */
        require(rawSatoshis <= MAX_BTC_ADDR_BALANCE_SATOSHIS, "HEX: CHK: rawSatoshis");

        /* Enforce the minimum stake time for the auto-stake from this claim */
        require(autoStakeDays >= MIN_AUTO_STAKE_DAYS, "HEX: autoStakeDays lower than minimum");

        /* Ensure signature matches the claim message containing the Eth address and claimParamHash */
        {
            bytes32 claimParamHash = 0;

            if (claimToAddr != msg.sender) {
                /* Claimer did not send this, so claim params must be signed */
                claimParamHash = keccak256(
                    abi.encodePacked(MERKLE_TREE_ROOT, autoStakeDays, referrerAddr)
                );
            }

            require(
                claimMessageMatchesSignature(
                    claimToAddr,
                    claimParamHash,
                    pubKeyX,
                    pubKeyY,
                    claimFlags,
                    v,
                    r,
                    s
                ),
                "HEX: Signature mismatch"
            );
        }

        /* Derive BTC address from public key */
        bytes20 btcAddr = pubKeyToBtcAddress(pubKeyX, pubKeyY, claimFlags);

        /* Ensure BTC address has not yet been claimed */
        require(!btcAddressClaims[btcAddr], "HEX: BTC address balance already claimed");

        /* Ensure BTC address is part of the Merkle tree */
        require(
            _btcAddressIsValid(btcAddr, rawSatoshis, proof),
            "HEX: BTC address or balance unknown"
        );

        /* Mark BTC address as claimed */
        btcAddressClaims[btcAddr] = true;

        return _satoshisClaimSync(
            rawSatoshis,
            claimToAddr,
            btcAddr,
            claimFlags,
            autoStakeDays,
            referrerAddr
        );
    }

    function _satoshisClaimSync(
        uint256 rawSatoshis,
        address claimToAddr,
        bytes20 btcAddr,
        uint8 claimFlags,
        uint256 autoStakeDays,
        address referrerAddr
    )
        private
        returns (uint256 totalClaimedHearts)
    {
        GlobalsCache memory g;
        GlobalsCache memory gSnapshot;
        _globalsLoad(g, gSnapshot);

        totalClaimedHearts = _satoshisClaim(
            g,
            rawSatoshis,
            claimToAddr,
            btcAddr,
            claimFlags,
            autoStakeDays,
            referrerAddr
        );

        _globalsSync(g, gSnapshot);

        return totalClaimedHearts;
    }

    /**
     * @dev Credit an Eth address with the Hearts value of a raw Satoshis balance
     * @param g Cache of stored globals
     * @param rawSatoshis Raw BTC address balance in Satoshis
     * @param claimToAddr Destination Eth address for the claimed Hearts to be sent
     * @param btcAddr Bitcoin address (binary; no base58-check encoding)
     * @param autoStakeDays Number of days to auto-stake, subject to minimum auto-stake days
     * @param referrerAddr Eth address of referring user (optional; 0x0 for no referrer)
     * @return Total number of Hearts credited, if successful
     */
    function _satoshisClaim(
        GlobalsCache memory g,
        uint256 rawSatoshis,
        address claimToAddr,
        bytes20 btcAddr,
        uint8 claimFlags,
        uint256 autoStakeDays,
        address referrerAddr
    )
        private
        returns (uint256 totalClaimedHearts)
    {
        /* Allowed only during the claim phase */
        require(g._currentDay >= CLAIM_PHASE_START_DAY, "HEX: Claim phase has not yet started");
        require(g._currentDay < CLAIM_PHASE_END_DAY, "HEX: Claim phase has ended");

        /* Check if log data needs to be updated */
        _dailyDataUpdateAuto(g);

        /* Sanity check */
        require(
            g._claimedBtcAddrCount < CLAIMABLE_BTC_ADDR_COUNT,
            "HEX: CHK: _claimedBtcAddrCount"
        );

        (uint256 adjSatoshis, uint256 claimedHearts, uint256 claimBonusHearts) = _calcClaimValues(
            g,
            rawSatoshis
        );

        /* Increment claim count to track viral rewards */
        g._claimedBtcAddrCount++;

        totalClaimedHearts = _remitBonuses(
            claimToAddr,
            btcAddr,
            claimFlags,
            rawSatoshis,
            adjSatoshis,
            claimedHearts,
            claimBonusHearts,
            referrerAddr
        );

        /* Auto-stake a percentage of the successful claim */
        uint256 autoStakeHearts = totalClaimedHearts * AUTO_STAKE_CLAIM_PERCENT / 100;
        _stakeStart(g, autoStakeHearts, autoStakeDays, true);

        /* Mint remaining claimed Hearts to claim address */
        _mint(claimToAddr, totalClaimedHearts - autoStakeHearts);

        return totalClaimedHearts;
    }

    function _remitBonuses(
        address claimToAddr,
        bytes20 btcAddr,
        uint8 claimFlags,
        uint256 rawSatoshis,
        uint256 adjSatoshis,
        uint256 claimedHearts,
        uint256 claimBonusHearts,
        address referrerAddr
    )
        private
        returns (uint256 totalClaimedHearts)
    {
        totalClaimedHearts = claimedHearts + claimBonusHearts;

        uint256 originBonusHearts = claimBonusHearts;

        if (referrerAddr == address(0)) {
            /* No referrer */
            _emitClaim(
                claimToAddr,
                btcAddr,
                claimFlags,
                rawSatoshis,
                adjSatoshis,
                totalClaimedHearts,
                referrerAddr
            );
        } else {
            /* Referral bonus of 10% of total claimed Hearts to claimer */
            uint256 referralBonusHearts = totalClaimedHearts / 10;

            totalClaimedHearts += referralBonusHearts;

            /* Then a cumulative referrer bonus of 20% to referrer */
            uint256 referrerBonusHearts = totalClaimedHearts / 5;

            originBonusHearts += referralBonusHearts + referrerBonusHearts;

            if (referrerAddr == claimToAddr) {
                /* Self-referred */
                totalClaimedHearts += referrerBonusHearts;
                _emitClaim(
                    claimToAddr,
                    btcAddr,
                    claimFlags,
                    rawSatoshis,
                    adjSatoshis,
                    totalClaimedHearts,
                    referrerAddr
                );
            } else {
                /* Referred by different address */
                _emitClaim(
                    claimToAddr,
                    btcAddr,
                    claimFlags,
                    rawSatoshis,
                    adjSatoshis,
                    totalClaimedHearts,
                    referrerAddr
                );
                _mint(referrerAddr, referrerBonusHearts);
            }
        }

        _mint(ORIGIN_ADDR, originBonusHearts);

        return totalClaimedHearts;
    }

    function _emitClaim(
        address claimToAddr,
        bytes20 btcAddr,
        uint8 claimFlags,
        uint256 rawSatoshis,
        uint256 adjSatoshis,
        uint256 claimedHearts,
        address referrerAddr
    )
        private
    {
        emit Claim( // (auto-generated event)
            uint256(uint40(block.timestamp))
                | (uint256(uint56(rawSatoshis)) << 40)
                | (uint256(uint56(adjSatoshis)) << 96)
                | (uint256(claimFlags) << 152)
                | (uint256(uint72(claimedHearts)) << 160),
            uint256(uint160(msg.sender)),
            btcAddr,
            claimToAddr,
            referrerAddr
        );

        if (claimToAddr == msg.sender) {
            return;
        }

        emit ClaimAssist( // (auto-generated event)
            uint256(uint40(block.timestamp))
                | (uint256(uint160(btcAddr)) << 40)
                | (uint256(uint56(rawSatoshis)) << 200),
            uint256(uint56(adjSatoshis))
                | (uint256(uint160(claimToAddr)) << 56)
                | (uint256(claimFlags) << 216),
            uint256(uint72(claimedHearts))
                | (uint256(uint160(referrerAddr)) << 72),
            msg.sender
        );
    }

    function _calcClaimValues(GlobalsCache memory g, uint256 rawSatoshis)
        private
        pure
        returns (uint256 adjSatoshis, uint256 claimedHearts, uint256 claimBonusHearts)
    {
        /* Apply Silly Whale reduction */
        adjSatoshis = _adjustSillyWhale(rawSatoshis);
        require(
            g._claimedSatoshisTotal + adjSatoshis <= CLAIMABLE_SATOSHIS_TOTAL,
            "HEX: CHK: _claimedSatoshisTotal"
        );
        g._claimedSatoshisTotal += adjSatoshis;

        uint256 daysRemaining = CLAIM_PHASE_END_DAY - g._currentDay;

        /* Apply late-claim reduction */
        adjSatoshis = _adjustLateClaim(adjSatoshis, daysRemaining);
        g._unclaimedSatoshisTotal -= adjSatoshis;

        /* Convert to Hearts and calculate speed bonus */
        claimedHearts = adjSatoshis * HEARTS_PER_SATOSHI;
        claimBonusHearts = _calcSpeedBonus(claimedHearts, daysRemaining);

        return (adjSatoshis, claimedHearts, claimBonusHearts);
    }

    /**
     * @dev Apply Silly Whale adjustment
     * @param rawSatoshis Raw BTC address balance in Satoshis
     * @return Adjusted BTC address balance in Satoshis
     */
    function _adjustSillyWhale(uint256 rawSatoshis)
        private
        pure
        returns (uint256)
    {
        if (rawSatoshis < 1000e8) {
            /* For < 1,000 BTC: no penalty */
            return rawSatoshis;
        }
        if (rawSatoshis >= 10000e8) {
            /* For >= 10,000 BTC: penalty is 75%, leaving 25% */
            return rawSatoshis / 4;
        }
        /*
            For 1,000 <= BTC < 10,000: penalty scales linearly from 50% to 75%

            penaltyPercent  = (btc - 1000) / (10000 - 1000) * (75 - 50) + 50
                            = (btc - 1000) / 9000 * 25 + 50
                            = (btc - 1000) / 360 + 50

            appliedPercent  = 100 - penaltyPercent
                            = 100 - ((btc - 1000) / 360 + 50)
                            = 100 - (btc - 1000) / 360 - 50
                            = 50 - (btc - 1000) / 360
                            = (18000 - (btc - 1000)) / 360
                            = (18000 - btc + 1000) / 360
                            = (19000 - btc) / 360

            adjustedBtc     = btc * appliedPercent / 100
                            = btc * ((19000 - btc) / 360) / 100
                            = btc * (19000 - btc) / 36000

            adjustedSat     = 1e8 * adjustedBtc
                            = 1e8 * (btc * (19000 - btc) / 36000)
                            = 1e8 * ((sat / 1e8) * (19000 - (sat / 1e8)) / 36000)
                            = 1e8 * (sat / 1e8) * (19000 - (sat / 1e8)) / 36000
                            = (sat / 1e8) * 1e8 * (19000 - (sat / 1e8)) / 36000
                            = (sat / 1e8) * (19000e8 - sat) / 36000
                            = sat * (19000e8 - sat) / 36000e8
        */
        return rawSatoshis * (19000e8 - rawSatoshis) / 36000e8;
    }

    /**
     * @dev Apply late-claim adjustment to scale claim to zero by end of claim phase
     * @param adjSatoshis Adjusted BTC address balance in Satoshis (after Silly Whale)
     * @param daysRemaining Number of reward days remaining in claim phase
     * @return Adjusted BTC address balance in Satoshis (after Silly Whale and Late-Claim)
     */
    function _adjustLateClaim(uint256 adjSatoshis, uint256 daysRemaining)
        private
        pure
        returns (uint256)
    {
        /*
            Only valid from CLAIM_PHASE_DAYS to 1, and only used during that time.

            adjustedSat = sat * (daysRemaining / CLAIM_PHASE_DAYS) * 100%
                        = sat *  daysRemaining / CLAIM_PHASE_DAYS
        */
        return adjSatoshis * daysRemaining / CLAIM_PHASE_DAYS;
    }

    /**
     * @dev Calculates speed bonus for claiming earlier in the claim phase
     * @param claimedHearts Hearts claimed from adjusted BTC address balance Satoshis
     * @param daysRemaining Number of claim days remaining in claim phase
     * @return Speed bonus in Hearts
     */
    function _calcSpeedBonus(uint256 claimedHearts, uint256 daysRemaining)
        private
        pure
        returns (uint256)
    {
        /*
            Only valid from CLAIM_PHASE_DAYS to 1, and only used during that time.
            Speed bonus is 20% ... 0% inclusive.

            bonusHearts = claimedHearts  * ((daysRemaining - 1)  /  (CLAIM_PHASE_DAYS - 1)) * 20%
                        = claimedHearts  * ((daysRemaining - 1)  /  (CLAIM_PHASE_DAYS - 1)) * 20/100
                        = claimedHearts  * ((daysRemaining - 1)  /  (CLAIM_PHASE_DAYS - 1)) / 5
                        = claimedHearts  *  (daysRemaining - 1)  / ((CLAIM_PHASE_DAYS - 1)  * 5)
        */
        return claimedHearts * (daysRemaining - 1) / ((CLAIM_PHASE_DAYS - 1) * 5);
    }
}

contract TransformableToken is UTXORedeemableToken {
    /**
     * @dev PUBLIC FACING: Enter the tranform lobby for the current round
     * @param referrerAddr Eth address of referring user (optional; 0x0 for no referrer)
     */
    function xfLobbyEnter(address referrerAddr)
        external
        payable
    {
        uint256 enterDay = _currentDay();
        require(enterDay < CLAIM_PHASE_END_DAY, "HEX: Lobbies have ended");

        uint256 rawAmount = msg.value;
        require(rawAmount != 0, "HEX: Amount required");

        XfLobbyQueueStore storage qRef = xfLobbyMembers[enterDay][msg.sender];

        uint256 entryIndex = qRef.tailIndex++;

        qRef.entries[entryIndex] = XfLobbyEntryStore(uint96(rawAmount), referrerAddr);

        xfLobby[enterDay] += rawAmount;

        _emitXfLobbyEnter(enterDay, entryIndex, rawAmount, referrerAddr);
    }

    /**
     * @dev PUBLIC FACING: Leave the transform lobby after the round is complete
     * @param enterDay Day number when the member entered
     * @param count Number of queued-enters to exit (optional; 0 for all)
     */
    function xfLobbyExit(uint256 enterDay, uint256 count)
        external
    {
        require(enterDay < _currentDay(), "HEX: Round is not complete");

        XfLobbyQueueStore storage qRef = xfLobbyMembers[enterDay][msg.sender];

        uint256 headIndex = qRef.headIndex;
        uint256 endIndex;

        if (count != 0) {
            require(count <= qRef.tailIndex - headIndex, "HEX: count invalid");
            endIndex = headIndex + count;
        } else {
            endIndex = qRef.tailIndex;
            require(headIndex < endIndex, "HEX: count invalid");
        }

        uint256 waasLobby = _waasLobby(enterDay);
        uint256 _xfLobby = xfLobby[enterDay];
        uint256 totalXfAmount = 0;
        uint256 originBonusHearts = 0;

        do {
            uint256 rawAmount = qRef.entries[headIndex].rawAmount;
            address referrerAddr = qRef.entries[headIndex].referrerAddr;

            delete qRef.entries[headIndex];

            uint256 xfAmount = waasLobby * rawAmount / _xfLobby;

            if (referrerAddr == address(0)) {
                /* No referrer */
                _emitXfLobbyExit(enterDay, headIndex, xfAmount, referrerAddr);
            } else {
                /* Referral bonus of 10% of xfAmount to member */
                uint256 referralBonusHearts = xfAmount / 10;

                xfAmount += referralBonusHearts;

                /* Then a cumulative referrer bonus of 20% to referrer */
                uint256 referrerBonusHearts = xfAmount / 5;

                if (referrerAddr == msg.sender) {
                    /* Self-referred */
                    xfAmount += referrerBonusHearts;
                    _emitXfLobbyExit(enterDay, headIndex, xfAmount, referrerAddr);
                } else {
                    /* Referred by different address */
                    _emitXfLobbyExit(enterDay, headIndex, xfAmount, referrerAddr);
                    _mint(referrerAddr, referrerBonusHearts);
                }
                originBonusHearts += referralBonusHearts + referrerBonusHearts;
            }

            totalXfAmount += xfAmount;
        } while (++headIndex < endIndex);

        qRef.headIndex = uint40(headIndex);

        if (originBonusHearts != 0) {
            _mint(ORIGIN_ADDR, originBonusHearts);
        }
        if (totalXfAmount != 0) {
            _mint(msg.sender, totalXfAmount);
        }
    }

    /**
     * @dev PUBLIC FACING: Release any value that has been sent to the contract
     */
    function xfLobbyFlush()
        external
    {
        require(address(this).balance != 0, "HEX: No value");

        FLUSH_ADDR.transfer(address(this).balance);
    }

    /**
     * @dev PUBLIC FACING: External helper to return multiple values of xfLobby[] with
     * a single call
     * @param beginDay First day of data range
     * @param endDay Last day (non-inclusive) of data range
     * @return Fixed array of values
     */
    function xfLobbyRange(uint256 beginDay, uint256 endDay)
        external
        view
        returns (uint256[] memory list)
    {
        require(
            beginDay < endDay && endDay <= CLAIM_PHASE_END_DAY && endDay <= _currentDay(),
            "HEX: invalid range"
        );

        list = new uint256[](endDay - beginDay);

        uint256 src = beginDay;
        uint256 dst = 0;
        do {
            list[dst++] = uint256(xfLobby[src++]);
        } while (src < endDay);

        return list;
    }

    /**
     * @dev PUBLIC FACING: Return a current lobby member queue entry.
     * Only needed due to limitations of the standard ABI encoder.
     * @param memberAddr Eth address of the lobby member
     * @param entryId 49 bit compound value. Top 9 bits: enterDay, Bottom 40 bits: entryIndex
     * @return 1: Raw amount that was entered with; 2: Referring Eth addr (optional; 0x0 for no referrer)
     */
    function xfLobbyEntry(address memberAddr, uint256 entryId)
        external
        view
        returns (uint256 rawAmount, address referrerAddr)
    {
        uint256 enterDay = entryId >> XF_LOBBY_ENTRY_INDEX_SIZE;
        uint256 entryIndex = entryId & XF_LOBBY_ENTRY_INDEX_MASK;

        XfLobbyEntryStore storage entry = xfLobbyMembers[enterDay][memberAddr].entries[entryIndex];

        require(entry.rawAmount != 0, "HEX: Param invalid");

        return (entry.rawAmount, entry.referrerAddr);
    }

    /**
     * @dev PUBLIC FACING: Return the lobby days that a user is in with a single call
     * @param memberAddr Eth address of the user
     * @return Bit vector of lobby day numbers
     */
    function xfLobbyPendingDays(address memberAddr)
        external
        view
        returns (uint256[XF_LOBBY_DAY_WORDS] memory words)
    {
        uint256 day = _currentDay() + 1;

        if (day > CLAIM_PHASE_END_DAY) {
            day = CLAIM_PHASE_END_DAY;
        }

        while (day-- != 0) {
            if (xfLobbyMembers[day][memberAddr].tailIndex > xfLobbyMembers[day][memberAddr].headIndex) {
                words[day >> 8] |= 1 << (day & 255);
            }
        }

        return words;
    }

    function _waasLobby(uint256 enterDay)
        private
        returns (uint256 waasLobby)
    {
        if (enterDay >= CLAIM_PHASE_START_DAY) {
            GlobalsCache memory g;
            GlobalsCache memory gSnapshot;
            _globalsLoad(g, gSnapshot);

            _dailyDataUpdateAuto(g);

            uint256 unclaimed = dailyData[enterDay].dayUnclaimedSatoshisTotal;
            waasLobby = unclaimed * HEARTS_PER_SATOSHI / CLAIM_PHASE_DAYS;

            _globalsSync(g, gSnapshot);
        } else {
            waasLobby = WAAS_LOBBY_SEED_HEARTS;
        }
        return waasLobby;
    }

    function _emitXfLobbyEnter(
        uint256 enterDay,
        uint256 entryIndex,
        uint256 rawAmount,
        address referrerAddr
    )
        private
    {
        emit XfLobbyEnter( // (auto-generated event)
            uint256(uint40(block.timestamp))
                | (uint256(uint96(rawAmount)) << 40),
            msg.sender,
            (enterDay << XF_LOBBY_ENTRY_INDEX_SIZE) | entryIndex,
            referrerAddr
        );
    }

    function _emitXfLobbyExit(
        uint256 enterDay,
        uint256 entryIndex,
        uint256 xfAmount,
        address referrerAddr
    )
        private
    {
        emit XfLobbyExit( // (auto-generated event)
            uint256(uint40(block.timestamp))
                | (uint256(uint72(xfAmount)) << 40),
            msg.sender,
            (enterDay << XF_LOBBY_ENTRY_INDEX_SIZE) | entryIndex,
            referrerAddr
        );
    }
}

contract HEX is TransformableToken {
    constructor()
        public
    {
        /* Initialize global shareRate to 1 */
        globals.shareRate = uint40(1 * SHARE_RATE_SCALE);

        /* Initialize dailyDataCount to skip pre-claim period */
        globals.dailyDataCount = uint16(PRE_CLAIM_DAYS);

        /* Add all Satoshis from UTXO snapshot to contract */
        globals.claimStats = _claimStatsEncode(
            0, // _claimedBtcAddrCount
            0, // _claimedSatoshisTotal
            FULL_SATOSHIS_TOTAL // _unclaimedSatoshisTotal
        );
    }

    function() external payable {}
}