using System;

public class Program

{

    public static void Main()

    {

        var genericHi = new Action(() => Console.WriteLine("Hello World!"));

        genericHi();

        var personalizedHi =

            new Action<string, string>((firstName, lastName) => Console.WriteLine($"Hello, {firstName} {lastName}!"));      

        personalizedHi("Katie", "Smith");

        var sayHiToEveryone =

            new Action<string, string, string>((name1, name2, name3) =>

                                               {

                                                   Console.WriteLine($"Hi {name1}!");

                                                   Console.WriteLine($"Hi {name2}!");

                                                   Console.WriteLine($"Hi {name3}!");

                                               });

        sayHiToEveryone("Larry", "Curly", "Moe");

        Action genericBye = () => Console.WriteLine("Goodbye World! (but not, you know.. permanently)");

        genericBye();

        Action<string, string> personalizedBye = (firstName, lastName) => Console.WriteLine($"Goodbye, {firstName} {lastName}!");

        personalizedBye("Katie", "Smith");

    }

}