#0JPQsNCy0YDQuNC70Y7QuiDQkNC90LTRgNGW0Lk=
def gcd(a, b):
while a != b:
if a>b:
a = a -b
else:
b = b - a
u = a
return u
k = gcd(21, 14)
print(k)
IzBKUFFzTkN5MFlEUXVOQzcwWTdRdWlEUWtOQzkwTFRSZ05HVzBMaz0KZGVmIGdjZChhLCBiKToKCXdoaWxlIGEgIT0gYjoKCQlpZiBhPmI6CgkJCWEgPSBhIC1iCgkJZWxzZToKCQkJYiA9IGIgLSBhCgl1ID0gYQoJcmV0dXJuIHUKCQprID0gZ2NkKDIxLCAxNCkKcHJpbnQoayk=