import java.util.Scanner;

public class GCD
{
 
    
    public int gcd(int x, int y)
    {
	return 1;
    }
    
    
    public static void main(String[] args)
    {
	Scanner scanner = new Scanner(System.in);
	GCD gcd = new GCD();
	while (true)
	{
	    System.out.println("First integer:");
	    int xx = scanner.nextInt();
	    System.out.println("Second integer:");
	    int yy = scanner.nextInt();
	    if (xx==0 || yy==0)
	    {
		System.out.println("Goofbye");
		return;
	    }
	    System.out.println("GCD of " + xx + " " + yy + " is " + gcd.gcdb(xx, yy));
	}
    }
    
    
    
    
    
    public int gcdb(int x, int y)
    {
	if (x<y)
	    return gcdb(y,x);
	if (x%y==0)
	    return y;
	return gcdb(y, x%y);
    }
}