using System;

​

public static class Program

{

    public static void Main(string[] args)

    {

     MyClassB b = new MyClassB();

     MyClassA a = b;

     MyClassC c = new MyClassC();

​

     a.call();

     b.call();

     c.call();

​

     Console.ReadLine();

    }

}

​

class MyClassA

{

    public MyClassA()

    {

     Console.WriteLine("constructor A");

    }

    public void call()

    {

     Console.WriteLine("A");

    }

}

​

class MyClassB : MyClassA

{

    public MyClassB()

    {

     Console.WriteLine("constructor B");

    }

​

    public void call()

    {

     Console.WriteLine("B");

    }

}

class MyClassC : MyClassA

{

    public MyClassC()

    {

     Console.WriteLine("constructor C");

    }

​

    public void call()

    {

     Console.WriteLine("C");

    }

}

​