using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Func<string, string> f =

            s=>string.Concat(s.Reverse().Select((c,i)=>s[i]>96?char.ToLower(c):char.ToUpper(c)));

        Func<string, string> bonus = //can be fix with char.IsLetter(c) or c>64&c<91|c>96&c<123 ...

            s=>string.Concat(s.Reverse().Select((c,i)=>(char)(s[i]>96?c|32:c&~32)));

        Func<string, string> f2 =

            s=>string.Concat(s.Reverse().Select((c,i)=>s[i]>96?char.ToLower(c):char.ToUpper(c)));

        Console.WriteLine(f("Hello, Midnightas"));

        Console.WriteLine(f2("Hello, Midnightas"));

        Console.WriteLine(f("AlOiS"));

        Console.WriteLine(f2("AlOiS"));

        Console.WriteLine(f("AlOiS-c[o_O]p"));

        Console.WriteLine(f2("AlOiS-c[o_O]p"));

    }

}