#include <iostream>
using namespace std;

class shape {
protected:
    int width, height;
public:
    shape(int a = 0, int b = 0) {
        width = a;
        height = b;
    }
    virtual int area() {
        cout << "parent class area: " << endl;
        return 0;
    }
};

class rectangle: public shape {
public:
    rectangle(int a = 0, int b = 0) : shape(a, b) { }
    int area () {
        cout << "rectangle area: ";
        return (width * height);
    }
};

class triangle: public shape {
public:
    triangle(int a = 0, int b = 0) : shape(a, b) { }
    int area () {
        cout << "triangle area: ";
        return (width * height / 2);
    }
};

int main() {
    shape *pshape;
    rectangle rec(10, 7);
    triangle tri(10, 5);

    pshape = &rec;
    pshape->area();

    pshape = &tri;
    pshape->area();
    return 0;
}