using System;

public class Program

{

    public static void Main()

    {

        Derived d = new Derived();

        Base b = new Derived();

        d.PrintN();

        b.PrintN();

    }

    public abstract class Base

    {

        public Base() { N = 2; PrintN(); }

        public void PrintN() { Console.WriteLine(N); }

        public abstract int N { get; set; }

    }

    public class Derived : Base

    {

        public Derived() { N = 3; }

        public new void PrintN() { Console.WriteLine(2*N); }

        public override sealed int N { get; set; }

    }

}