// train.h

#include <vector>

class Car;

class Train {
public:
    Train();
    virtual ~Train();
    void add(Car *car);
    float currentMt() const;    // Current weight in metric tons (Mt)
private:
    std::vector<Car*> cars;
};

class Car {
public:
    Car();
    virtual ~Car();
    void brake();
    virtual float currentMt() const;
    virtual float maxMt() const = 0;
private:
    float measuredMt;           // weight as measured on scale
};

class Locomotive : public Car {
public:
    Locomotive();
    virtual void disengage();
    virtual void engage();
    float maxMt() const override;
};

class Wagon : public Car {
public:
    Wagon();
    virtual float volume() const = 0; // all volumes in cubic feet
    float maxMt() const override;
private:
    float unloadedMt;
};

class BoxCar : public Wagon {
public:
    BoxCar();
    float volume() const override;
};

class Tanker : public Wagon {
public:
    Tanker();
    float volume() const override;
    float maxMt() const override;
};