using System;

public class Program

{

    public interface IService

    {

        int DoAction();

    }

​

    public class Service1 : IService

    {

        public int DoAction()

        {

            return 1;

        }

    }

​

    public class Service2 : Service1, IService

    {

        new public int DoAction()

        {

            return 2;

        }

    }

​

    public static void Main()

    {

        IService service = new Service2();

        var result = service.DoAction();

        Console.WriteLine(result);

    }

}