static void Main(string[] args)
{
Academy p = new Academy("UCL", "Seebladsgade");
Student s1 = new Student(p, "Jens");
Student s2 = new Student(p, "Niels");
Student s3 = new Student(p, "Susan");
p.Attach(s1);
p.Attach(s2);
p.Attach(s3);
p.Message = "Så er der julefrokost!";
p.Detach(s2);
p.Message = "Så er der fredagsbar!";
Console.ReadLine();
}