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.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
	    int a = in.nextInt();
	    int b = in.nextInt();
	    int gsd = 1;
	    if (a>=b) {
		    while (a%b !=0)
		    {
		    	int aim = b;
		        b=a%aim;
		        a=aim;
			    gsd=b;
		    }
		    System.out.println(gsd);
	    }
	    else {
	    	while (b%a !=0) {
	    		int aim = a;
	    	    a=b%aim;
	    	    b=aim;
			    gsd=a;
	    	}
	    	System.out.println(gsd);
	    }
	    in.close();
	}
}