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 JAVA (judge verdict: Wrong Answer)

import java.util.Scanner;

public class Main{

	public static void main(String[] args) {
            Scanner in = new Scanner(System.in);
            int a = in.nextInt();
            int b = in.nextInt();
            int z = 0;
            for(int i = 1; 0 <= i; i--) {
            	if(a % i == 0 && b % i == 0) {
            		z = i;
            		System.out.println(z);
            		break;
            	}
            }
            
            
	}
}