using System;

​

​

public interface IService

    {

        void Serve();

    }

    public class Service : IService

    {

        public void Serve()

        {

            Console.WriteLine("Service Called");

        }

    }

​

public class Client

{

    private IService _service;

    public Client(IService service)

    {

        this._service = service;

    }

    public void Start()

    {

        Console.WriteLine("Service Started");

        this._service.Serve();

    }

}

public class Program

{   

    public static void Main()

    {

        Client client = new Client(new Service());

        client.Start();

    }

}