function createWinner() public onlyOwner jackpotAreActive {
        uint64 tmNow = uint64(block.timestamp);
        require(tmNow >= nextJackpotTime);
        require(jackpotPlayer.length > 0);
        uint random = rand() % jackpotPlayer.length;
        address winner = jackpotPlayer[random - 1];
        sendJackpot(winner);
    }