@Override
    public void update(Observable o, Object arg) {
        if (arg != null && arg instanceof Integer) {
            Integer timestamp = (Integer) arg;
            if (leaveMap.containsKey(timestamp)) {
                for(Car auto : leaveMap.get(timestamp))
                    cs.addToExitQueue(auto);
                leaveMap.remove(timestamp);
            }
        }
    }