using System;

​

public class Program

{

    public static void Main()

    {

        // split string 

        var hello = "Hello World";

        // splt using l as the search substring

        string[] words = hello.ToLower().Split("l");

        var resultString = "";

        for (int i = 0; i < words.Length; i++)

        {

            // now we have split the string how do find the missing 'l' and wrap a span around them

            resultString += words[i].ToString();

        }

        // result is heo word

        Console.WriteLine(resultString);

        // Trying to get the result to be "He<span>l</span><span>l</span>o Wor<span>l<span>d

    }

}