using System;

​

public interface IAnimal

{

    void ChangeName(string newName);

}

​

public class Animal : IAnimal

{

    protected string _name { get; set; }

    public string Name { get { return _name; } }

    public Animal()

    {

        _name = this.GetType().Name;

    }

    public virtual void ChangeName(string newName)

    {

        _name = newName;    

    }

}

​

public class Bear : Animal

{

    public override void ChangeName(string newName)

    {

        _name = newName + " the Bear";

    }

    public void Attack(Animal animal)

    {

        Console.WriteLine(Name + " has attacked " + animal.Name + "!");

    }

}

​

public class Duck : Animal

{

    public void Fly()

    {

        Console.WriteLine(Name + " has started flying!");

    }

}

​

public class Program

{

    public static void Main(string[] args)

    {

        var bear = new Bear();

        var duck = new Duck();

        Console.WriteLine("bear: \""+bear.Name+"\"");

        Console.WriteLine("duck: \""+duck.Name+"\"");

        bear.Attack(duck);

        bear.ChangeName("Bob");

        duck.ChangeName("Deidre");

        Console.WriteLine("bear: \""+bear.Name+"\"");

        Console.WriteLine("duck: \""+duck.Name+"\"");

        duck.Fly();

​

    }

}