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 Python3 (judge verdict: Accepted)

import math
from functools import reduce

def gcd(*numbers):
    return reduce(math.gcd,numbers)
    
x,y=map(int,input().split())
k=0
if x<y:
    k=x
    x=y
    y=k

z=x%y

n=(gcd(y,z))
print(n)