public static ModNum Pow(ModNum val, ulong count)
{
return(count == 0 ? new ModNum(1) :
count == 1 ? val :
count == 2 ? val * val :
count % 2 == 0 ?
Pow(Pow(val, count / 2), 2) :
Pow(Pow(val, count / 2), 2) * val);
}
private static ModNum Inverse(ModNum val)
{
return(Pow(val, mod - 2));
}