Write a C# Sharp program to create a new string of length 2, using first two characters of a given string. If the given string length is less than 2 use '#' as missing characters

using System;

namespace exercises
{
   class Program
    {       
        static void Main(string[] args)
        {
            Console.WriteLine(test("Hello"));
            Console.WriteLine(test("Python"));
            Console.WriteLine(test("a"));
            Console.WriteLine(test(""));
            Console.ReadLine();
        }
        
      public static string test(string s1)
        {
           if (s1.Length >= 2)
            {
                s1 = s1.Substring(0, 2);
            }
            else if (s1.Length > 0)
            {
                s1 = s1.Substring(0, 1) + "#";
            }
            else
            {
                s1 = "##";
            }

            return s1;
        }
  }
}