using System;

​

public static class Program

{

    public static void Main(string[] args)

    {

        var fc = new FamilyCar();

        var sc = new SportCar();

        fc.Start();

        fc.Stop();

        sc.Start();

        sc.Stop();

    }

}

​

public interface IVehicle

{

    void Start();

    void Stop();

}

​

public abstract class BaseCar : IVehicle

{

    public void Start()

    {

    }

​

    public void Stop()

    {

    }

}

​

public class SportCar : BaseCar

{

}

​

public class FamilyCar : BaseCar

{

}