public void placePerson(Person person, Room room) throws IllegalArgumentException{
        if(person == null){throw new IllegalArgumentException();}
        if(room ==null){throw new IllegalArgumentException();}
        List<Person> help = new ArrayList<Person>();

        for(Room r : personMap.keySet()){
            List<Person> p = new ArrayList<Person>();
            p.addAll(personMap.get(r));

            if(p.contains(person)){
                    help.addAll(personMap.get(room)); //naplnim novu miestnost
                    personMap.remove(room);
                    help.add(person);
                    personMap.put(room,help);

                    help.clear(); //cistenie

                    help.addAll(personMap.get(r));
                    help.remove(person);
                    personMap.remove(room);
                    personMap.put(room,help);
                }

            p.clear();
        }
    }