using System;

​

public interface IService

{

     void Display();

     void Print()

     {

        System.Console.WriteLine("Print");

     }

}

​

public class Service : IService

{

    public void Display()        

    {

        Console.WriteLine("Display");

    }

}

public class Reposiory : Service

{

    public void PrintRepository()

    {

        System.Console.WriteLine("Print");

    }

}

​

public class Program

{

    public static void Main()

    {

        IService service = new Reposiory();

        //service.Display();

        //service.Print();

    }

}