static void Main(string[] args) { ISubject subject = new Subject(); var third = new Classes.Observer("Third"); subject.RegisterObserver(new Classes.Observer("First")); subject.RegisterObserver(new Classes.Observer("Second")); subject.RegisterObserver(third); subject.SetState(100, 20, 30); subject.RemoveObserver(third); subject.SetState(50, 3, 17); Console.ReadKey(); }