using System;

​

public class Program

{

    public static void Main()

    {

    Console.WriteLine(StringHelper.ReverseString("MINE"));

    Console.WriteLine(StringHelper.ReverseString("ESEN"));

    Console.WriteLine(StringHelper.ReverseString("MINE ESEN"));

    }

}

​

static class StringHelper

{

    /// <summary>

    /// Receives string and returns the string with its letters reversed.

    /// </summary>

    public static string ReverseString(string s)

    {

    char[] arr = s.ToCharArray();

    Array.Reverse(arr);

    return new string(arr);

    }

}

​

​