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: Wrong Answer)

a,b = map(int,input().split())
def gcd(x,y):
    z = max(x,y)  %  min(x,y)
    if z == 0 :
        return [min(x,y),0]
    return gcd(max(x,y),z)

L = gcd(a,b)
K = []
for i in reversed( (range(1,L[0] )) ) :
    if a % i == 0 and b % i == 0:
        K.append(i)

print(max(K))