static void Main(string[] args)
{
MessageSubscriberOne s1 = new MessageSubscriberOne();
MessageSubscriberTwo s2 = new MessageSubscriberTwo();
MessageSubscriberThree s3 = new MessageSubscriberThree();
MessagePublisher p = new MessagePublisher();
p.Attach(s1);
p.Attach(s2);
p.Attach(s3);
p.ChangeState(2);
Console.ReadLine();
}