Write a C# Sharp program to create a new string using the first and last n characters from a given string of length at least n

using System;

namespace exercises
{
   class Program
    {       
        static void Main(string[] args)
        {
            Console.WriteLine(test("Hello", 1));
            Console.WriteLine(test("Python", 2));
            Console.WriteLine(test("on", 1));
            Console.WriteLine(test("o", 1));
            Console.ReadLine();
        }
        
         public static string test(string s1, int n)
         {
             return s1.Substring(0, n) + s1.Substring(s1.Length - n);
         }
  }
}