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.Scanner;
    
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String str = scanner.nextLine();
        String strArr[] = str.split(" ");
        
        int x = 0;
        int y = 0;
        int tmp_x = Integer.parseInt(strArr[0]);
        int tmp_y = Integer.parseInt(strArr[1]);
        
        if (tmp_x > tmp_y) {
            y = tmp_x;
            x = tmp_y;
        } else {
            x = tmp_x;
            y = tmp_y;
        }
        
        while(y > 0){
            int r = x % y;
            x = y;
            y = r;
        }

        System.out.println(x);
    }
}