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: Time Limit Exceeded)

import java.util.Scanner;

public class Main{
    public static void main(String [] args){
        Scanner am = new Scanner(System.in);
        int x =am.nextInt();
        int y =am.nextInt();
        int c=1;
        for(int a=1;a<=x && a<=y;a++){
            if(x%a==0 && y%a==0)c=a;
        }
        System.out.println(c);
      am.close();  
    }
}