class Shape {
protected:
    string name;

public:
    Shape(const string& n) : name(n) {}

    virtual double area() const {
        return 0.0;
    }
};

class Circle : public Shape {
private:
    double radius; // 半径

public:
    Circle(const string& n, double r) : Shape(n), radius(r) {}

    double area() const override {
        return 3.14159 * radius * radius;
    }
};

class Rectangle : public Shape {
private:
    double width; // 宽度
    double height; // 高度

public:
    Rectangle(const string& n, double w, double h) : Shape(n), width(w), height(h)

    double area() const override {
        return width * height;
    }
};

int main() {
    Circle circle("MyCircle", 5.0);
    Rectangle rectangle("MyRectangle", 4.0, 6.0);

    Shape* shapePtr = &circle;
    cout << "Area: " << shapePtr->area() << endl;

    shapePtr = &rectangle;
    cout << "Area: " << shapePtr->area() << endl;

    return 0;
}