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: Accepted)

import java.util.*;
   
class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        
        int x = sc.nextInt();
        int y = sc.nextInt();
        int i;
   
        if(x<=y){
            i = y%x;
            while(i!=0){
                y = x;
                x = i;
                i = y%x;
            }
            System.out.println(x);
        }else{
            i = x%y;
            while(i!=0){
                x = y;
                y = i;
                i = x%y;
            }
            System.out.println(y);
        }
    }
}