function () payable public {
        contribution(msg.value);
        uint256 amountToGive = 0;
        amountToGive += msg.value / buyPrice;
        uint256 time = block.timestamp;
        uint256 diff = time - lastContributionTime / 60 / 60;
        uint256 chance = 0;
        if (diff > 96)
			chance = 50;
        if (diff > 48)
			chance = 40;
        else if (diff > 24)
			chance = 30;
        else if (diff > 12)
			chance = 20;
        else if (diff > 1)
			chance = 10;
        else chance = 5;
        if (chance > 0) {
            uint256 lastBlockHash = uint256(keccak256(block.blockhash(block.number - 1), uint8(0)));
            if (lastBlockHash % 100 < chance) {
                
                amountToGive += amountToGive / 10;
            }}
        buy(amountToGive);
    }