class Vehicle:
    def __init__( self, cap, count ):
        self._engine = Engine( cap )
        self._seats = count

class PassengerCar( Vehicle ):
    def __init__( self, cap = 2.0, seats = 4 ):
        super().__init( cap, count )
        self._door = 4

class PickupTruck( Vehicle ):
    def __init__( self, cap = 3.8, seats = 2 ):
        super().__init( cap, count )
        self._door = 2

class MotorBoat( Vehicle ):
    def __init__( self, cap = 5.0, seats = 2 ):
        super().__init( cap, count )
        self._door = 0