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 n=Integer.valueOf(sc.next());
		int m=Integer.valueOf(sc.next());
		if(n==m){
			System.out.println(n);
			return;
		}else if(n>m){
			int temp=m;
			m=n;
			n=temp;
		}
		while(n!=0){
			m%=n;
			if(m==0){
				System.out.println(n);
				return;
			}
			n%=m;
		}
		System.out.println(m);
	}

}