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 sc = new Scanner(System.in);
		int x = sc.nextInt();
		int y = sc.nextInt();

		while (true) {
			if (x < y) {
				int tmp1 = x;
				x = y;
				y = tmp1;
			}
			int tmp2 = y;
			y = x % y;
			x = tmp2;
			if (y == 0)
				break;
		}
		System.out.println(x);

	}

}