using System;

public class Program

{

    //Factory Design Patern

    public interface Car 

    {

        public void Start();

    }

    public class Audi:Car

    {

        public void Start()

        {

            Console.WriteLine("Start Audi");

        }

    }

    public class BMW:Car

    {

        public void Start()

        {

            Console.WriteLine("Start BMW");

        }

    }

    public class CarFactory

    {

        public static Car getCarType(string carType)

        {

            if(carType == null)

                return null;

            else if(carType.Equals("Audi", StringComparison.OrdinalIgnoreCase))

                return new Audi();

            else if(carType.Equals("BMW", StringComparison.OrdinalIgnoreCase))

                return new BMW();

            return null;

        }

    }

    public static void Main()

    {

        Car audi = CarFactory.getCarType("audi");

        audi.Start();

        Car bmw = CarFactory.getCarType("bmw");

        bmw.Start();

    }

}