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: Accepted)

l = map(int,raw_input().split())
l.sort()
a,b = l
max = 0
while True:
    tmp = a%b
    if tmp == 0:
        max = b
        break
    a = b
    b = tmp
print max