using System;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine(HackerSpeak("I made a program that converts whatever I type into leet speek lol", false));

    }

​

    public static string HackerSpeak(string str)

    {

        string x = string.Empty;

        int counter = 0;

        foreach (char c in str)

        {

            if (c == 'a')

            {

                x = x.Insert(counter, "4");

            }

            else if (c == 'e')

            {

                x = x.Insert(counter, "3");

            }

            else if (c == 'i')

            {

                x = x.Insert(counter, "1");

            }

            else if (c == 'o')

            {

                x = x.Insert(counter, "0");

            }

            else if (c == 's')

            {

                x = x.Insert(counter, "5");

            }

            else

            {

                x = x.Insert(counter, c.ToString());

            }

​

            counter++;

        }

        //x = x.ToUpper();

        return x;

    }

    public static string HackerSpeak(string str, bool toUpper){

        str = str.ToLower();

        if(toUpper)

            return HackerSpeak(str).ToUpper();

        else

            return HackerSpeak(str).ToLower();

    }

}