用辗转相除法求两个正整数的最大公约数

def divisor(a, b):
    while True:
        r = a%b
        a = b
        b = r
        if r == 0:
            break
    return a

a = int(raw_input('a:'))
b = int(raw_input('b:'))
if a > b:
    c = divisor(a, b)
else:
    c = divisor(b, a)
print c