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;
class Main{
    public static void main(String[] args){
	int x,y,temp=0,max=0;
	
	Scanner scan = new Scanner(System.in);
	x = scan.nextInt();
	y = scan.nextInt();

	if(1>=x || x>=1000000000){
	    if(1>=y || y>=1000000000){
		System.exit(0);
	    }
	}
	
	if(x>=y){
	    temp = x % y;
	    while(temp!=0){
		x = y;
		y = temp;
		temp = x % y;
		max = y;
	    }
	}
	else {
	    temp = x % y;
	    while(temp!=0){
		y = x;
		x = temp;
		temp = y % x;
		max=x;
	    }
	}
	System.out.println(max);
    }
}