using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(WrapString("Hello World"));

        Console.WriteLine(WrapString("lowful"));

        Console.WriteLine(WrapString("Helpful"));

        Console.WriteLine(WrapString("Love"));

        Console.WriteLine(WrapString("Lost"));

        Console.WriteLine(WrapString(""));

    }

    public static string WrapString(string input)

    {

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

        return string.Join("<span>l</span>", words);

    }

}

​

​