using System;

​

internal class Program

{

    static void Main(string[] args)

    {

​

        Car c = new Car();

        Vehicle v = new Vehicle();

​

        Console.WriteLine(v.DisplayInfo());

        Console.WriteLine(c.DisplayInfo());

​

        Console.WriteLine();

​

        c.Year = 2017;

        c.Make = "Toyota";

        c.NumberOfDoors = 1;

​

        v.Make = "Subaru";

        v.Model = "XS";

​

        Console.WriteLine(v.DisplayInfo());

        Console.WriteLine(c.DisplayInfo());

    }

}

​

internal class Vehicle

{

    private string make;

    private string model;

    private int year;

​

    public string Make { get { return this.make; } set { this.make = value; } }

    public string Model { get { return this.model; } set { this.model = value; } }

    public int Year { get { return this.year; } set { this.year = value; } }

​

    public Vehicle()

    {

        this.make = "BMW";

        this.model = "BMW X3 Series";

        this.year = 2003;

    }

​

    public Vehicle(string make, string model, int year)

    {

        this.make = make;

        this.model = model;

        this.year = year;

    }

​

    public virtual string DisplayInfo()

    {

        return "the make is " + this.make + ", the model is " + this.model + ", and the year is " + this.year;

    }

}

​

internal class Car : Vehicle

{

    private int numberOfDoors;

    private bool isConvertible;

​

    public int NumberOfDoors { get { return this.numberOfDoors; } set { this.numberOfDoors = value; } }

    public bool IsConvertible {  get { return this.isConvertible; } set { this.isConvertible = value; } }

​

    public Car() : base()

    {

        this.numberOfDoors = 4;

        this.isConvertible = false;

    }

​

    public Car(int numberOfDoors, bool isConvertible, string make, string model, int year) : base(make, model, year)

    {

        this.numberOfDoors = numberOfDoors;

        this.isConvertible = isConvertible;

    }

​

    public override string DisplayInfo()

    {

        return base.DisplayInfo() + " and it has " + this.numberOfDoors + " doors and is " + (this.isConvertible? "a convertible":"not a convertible");

    }

}