using System;
public class Program
{
public static void Main()
var b = new B(10,"Hello111");
b.Do();
}
public class A
private readonly string message;
public A(string message)
this.message = message;
protected string Message => message;
public class B : A
private readonly int age;
public B(int age, string message) : base(message)
this.age = age;
public void Do()
Console.WriteLine(this.Message);