function buyAgain(uint256 _amount) public isHuman whenNotPaused {
        require(smallRound[bigId][smallId].startTime < block.timestamp, "The game has not started yet");
        require(smallRound[bigId][smallId].endTime > block.timestamp, "The game is over");
        uint256 _money = _amount.mul(getPrice());
        uint256 profit = getMyProfit(bigId);
        require(_amount > 0 && _money > 0);
        require(profit >= _money);
        bigRound[bigId].received[msg.sender] = _money.add(bigRound[bigId].received[msg.sender]);
        _buy(_amount, _money);
    }