static void Main(string[] args)
{
Imediator mediator = new ConcreteMediator();
IUser user1 = new ConcreteUser(mediator);
IUser user2 = new ConcreteUser(mediator);
mediator.AddUser(user1);
mediator.AddUser(user2);
user1.SendMessage("This is user number 1!");
user2.SendMessage("This is user number 2!");
}