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.*;

public class Main {
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);

    int x = scan.nextInt();
    int y = scan.nextInt();

    if(x < y){
      int swap = x;
      x = y;
      y = swap;
    }

    while(y > 0){
      int z = x % y;
      if(z == 0){
        break;
      }
      x = y;
      y = z;
    }

    System.out.println(y);
  }


}