// Trying to invoke the display function from a pointer, but
// now display is virtual function.

#include <iostream>
using namespace std;

class Shape {
  protected:
    int width, height;
  public:
    Shape() { width = height = 0; }
    Shape(int w, int h) { width = w; height = h; }
    virtual void display() const;
};

void Shape::display() const {
  cout << width << " " << height << endl; 
}

class Rectangle : public Shape {
  public:
    Rectangle() {}
    Rectangle(int w, int h) : Shape(w, h) { }
    int perimeter() const;
    void display() const;
};

int Rectangle::perimeter() const{
  return 2 * width + 2 * height;
}

void Rectangle::display() const {
  cout << "I am rectangle of width " << width 
       << " and height " << height << endl;
}

class Square: public Rectangle {
  public:
    Square() {}
    Square(int w) : Rectangle(w,w) {}
    void display() const;
};

void Square::display() const {
  cout << "I am square of side " << width << endl;
}


int main() {

    Shape *p;
    Shape *s;
    p = new Rectangle(4,8);
    s = new Shape(3,5);

    s->display();
    p->display();

    Shape *q = new Square(10);
    q->display();

  return 0;
}