#potęgowanie binarne (left-to-right)

def potegowanie(x, k):
    y = 1
    i = k.bit_length()
    while i >= 0:
        y = y**2
        if (k & 1) == 1:
            y = y*x
        k = k >> 1
        i = i - 1
    return y


def potegowanieimod(x, k, n):
    y = 1
    i = k.bit_length()
    while i >= 0:
        y = y**2 % n
        if (k & 1) == 1:
            y = y*x % n
        k = k >> 1
        i = i - 1
    return y


print(potegowanie(2, 6))

print(potegowanieimod(5, 2, 10))