class Shape

{

public:

virtual double GetArea()=0;

};

class Rectangle : public Shape

{

public:

Rectangle(double h, double w) : height(h), width(w){}

double GetArea(){ return height * width; }

private:

double height;

double width;

};

class Circle : public Shape

{

public:

Circle(double r):radius(r){}

double GetArea(){ return 3.14159 * radius * radius; }

private:

double radius;

};

class Square : public Rectangle

{

public:

Square(double l) : Rectangle(l, l){}

};