def powMod(x, y, mod):
 x = mpz(x)
 y = mpz(y)
 mod = mpz(mod)
 return pow(x, y, mod)

def powMod ( x , y , mod ) : x = mpz ( x ) y = mpz ( y ) mod = mpz ( mod ) return pow ( x , y , mod )
calculate and return x to the power of y mod mod .