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)

x,y = map(int,input().split())

if x == y:
    print(x)
else:
    while not (x == 1 and y == 1):
        if x > y:
            x = x % y
            if x == 0:
                print(y)
                break
            # print(f'{x} {y}')
        elif x < y:
            y = y % x
            if y == 0:
                print(x)
                break
            # print(f'{x} {y}')
    '''
    else:

        # xの約数を算出
        divisor_x = []
        for a in range(x):
            if x % (a+1) == 0:
                divisor_x.append(a+1)

        for a in divisor_x[::-1]:
            if y % a == 0:
                print(a)
                break
    '''