using System;

public class Program

{

    public static void Main()

    {

        Base b = new Base();

        OverClass o = new OverClass();

        b = o;

        o.Show();

        b.Show();

        NewClass n = new NewClass();

        b = n;

        n.Show();

        b.Show();

        SuperNewClass s = new SuperNewClass();

        b = s;

        s.ShowBase();

        b.Show();

    }

}

​

public class Base

{

    public virtual void Show()

    {

        Console.WriteLine("Hello from Base!");

    }

}

​

public class OverClass: Base

{

    public override sealed void Show()

    {

        Console.WriteLine("Hello from Over!");

    }

}

​

public class NewClass: Base

{

    public new void Show()

    {

        Console.WriteLine("Hello from New!");

    }

}

​

public class SealedOverClass:OverClass

{

    // public override void Show(){}  - error:cannot override inherited member 'OverClass.Show()' because it is sealed  

}

​

public class SuperNewClass:NewClass

{

    public void ShowBase()

    {

        base.Show();

    }

}