using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        var o = new Concrete("Test");

        o.print();

    }

    public abstract class A

    {

        protected string Szymon {get; set;}

        public void print(){

            Console.WriteLine($"Szymon: {Szymon}");

        }

    }

    public class Concrete : A {

        public Concrete(string str){

            Szymon = str;

        }       

    }

}