using System;

public class Program

{

    public class MyBase

    {

        protected int c = 5;

        protected MyBase()

        {

            Console.WriteLine("MyBase constr");

        }

        public void DoSomething(int a)

        {

            Console.WriteLine("MyBase");

        }

    }

​

    public class MyDerived : MyBase

    {

        public MyDerived(){

            Console.WriteLine("MyDerived constr");

        }

        public void DoSomething(long a)

        {

            Console.WriteLine("MyDerived");

        }

    }

    public class MyDerivedSecond : MyDerived

    {

        public MyDerivedSecond()

        {

            Console.WriteLine("MyDerivedSecond constr");

        }

        public void DoSomething(Int16 a)

        {

            Console.WriteLine("MyDerivedSecond");

        }

    }

    public static void Main()

    {

        MyDerived d = new MyDerivedSecond();

        MyBase b = d;

        d.DoSomething((int)5);

        b.DoSomething((Int16)6);

    }

}