Write a C# program to create a new string of four copies, taking last four characters from a given string. If the length of the given string is less than 4 return the original one

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

public class Exercise32 {
  static void Main(string[] args)
        {
           string str; 
           int l= 0;
           Console.Write("Input a string : ");
           str = Console.ReadLine();
           if (str.Length>4)
           {
              Console.WriteLine(str.Length < 4 ? str + str + str : str.Substring(str.Length - 4)+ str.Substring(str.Length - 4) + str.Substring(str.Length - 4) + str.Substring(str.Length - 4));
           }
        }
}