public Elevator callUp(Rider r){
		int startFloor = r.getFrom();
		while(true) {
			for(Elevator e : elevators) {
				synchronized(e){
					if(e.isGoingUp() && e.getFloor()<startFloor) {
						e.addRequest(r);
						return e;
					}
					else if(!e.isInTransit()) {
						e.addRequest(r);
						return e;
					}
				}
			}
		}
	}