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;