Problem:
Greatest Common Divisor

Write a program which finds the greatest common divisor of two natural numbers a and b

Input

a and b are given in a line sparated by a single space.

Output

Output the greatest common divisor of a and b.

Constrants

1 ≤ a, b ≤ 109

Hint

You can use the following observation:

For integers x and y, if x ≥ y, then gcd(x, y) = gcd(y, x%y)

Sample Input 1

54 20

Sample Output 1

2

Sample Input 2

147 105

Sample Output 2

21

Solution in Python (judge verdict: Wrong Answer)

import sys

for line in sys.stdin:
    lineA=line.strip()
    A=lineA.split()
    B=map(int,A)
    if B[0]<B[1]:
        p=B[1]
        B[1]=B[0]
        B[0]=p
    e=1

    while e != 0:
        e=B[0]%B[1]
        C=B[1]
        B[1]=e
        B[0]=C

    print B[1]