interface iVehicle {

	public void drive();
	public void stop();

}

class Car implements iVehicle {

	public void drive() {
		print("Driving...\n");
	}

	public void stop() {
		print("Stopping...\n");
	}

}

class MyCar extends Car {

	public void drive() {
		print("Driving my car...\n");
	}

} 

class Program {

	public void driveCar(iVehicle $vehicle) {
		$vehicle->drive();
		$vehicle->stop();
	}

	public void main() {
		object $car = new Car();
		object $mycar = new MyCar();
		$this->driveCar($car);
		$this->driveCar($mycar);
	}

}