using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

         N = 20;

         S= 0;m= 0;

         While (m <= n);

         S=1+2+3+...+n;

         S=S + m;

         S= 

        int n=20;

        while (n <= 9)

        {

          Console.WriteLine("Number : " + n);

          n++;

        }

}