public class LadderVehicleCounter extends VehicleCounter {
	
	public void count(Vehicle[] vehicles) {
		for (Vehicle vehicle: vehicles) {
			if (vehicle instanceof Car) ++numCars;
			else if (vehicle instanceof Bike) ++numBikes;
			else if (vehicle instanceof Motorbike) ++numMotorbikes;
			else throw new IllegalArgumentException("unknown type of vehicle: " + vehicle);
		}
	}
	
}