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: Wrong Answer)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

class Main{
	
	public static void main(String[] args) throws IOException {
		
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

//		 int n = Integer.parseInt(in.readLine());
		
		 String[] xy = in.readLine().split(" ");

		 int x=Integer.parseInt(xy[0]);
		 int y=Integer.parseInt(xy[1]);
		 

		 
		 int tmp;
		 while(x!=0){
			 
			 tmp=x%y;
			 y=x;
			 x=tmp;
			 
		 }
		 
		 System.out.println(y);
		
	}
}