import java.util.Scanner;
/**
 * Computs triangular numbers in a completely recursive way.
 **/
public class Triangular
{
    /**
     * Use recursion to add numers 1..num
     **/
    public int f(int num)
    {
	if (num==0) return 0;
	return num + f(num-1);
    }

    /**
     * Use recursion to do triangular numbers
     **/
    public int triangular(int num)
    {
	if (num==0) return 0;
	return f(num) + triangular(num-1);

    }

    /**
     * Gets input from user
     **/
    public static void main(String[] args)
    {
	Scanner scanner = new Scanner(System.in);
	Triangular tri = new Triangular();
	while (true)
	{
	    System.out.println("Integer:");
	    int xx = scanner.nextInt();
	    if (xx==0)
	    {
		System.out.println("Goofbye");
		return;
	    }
	    System.out.println("Trangular number " + xx + " is " + tri.triangular(xx));
	}
    }
}