function bchexdec($hex) {
        if(strlen($hex) == 1) {
            return hexdec($hex);
        } else {
            $remain = substr($hex, 0, -1);
            $last = substr($hex, -1);
            return bcadd(bcmul(16, bchexdec($remain)), hexdec($last));
        }
    }

$vyherce = bcmod(bchexdec($hash), $pocet_kandidatu) + 1;