public int Decrypt(int p, int q, int C, int e)
{
long n = p * q;
// Get phi(n)
// Call Euclidean Extended to get d
NumberTheory calc = new NumberTheory();
long d = calc.GetMultiplicativeInverse(e, calc.Phi(p, q));
// Get M = C^d mod d
int M = (int)calc.FastPower(C, d, n);
return(M);
}