#include <iostream>
#include <ctime>
#include <cstdlib>
using namespace std;


class Figura {
public:
    Figura *next;
    virtual void pole() {};
    virtual int pole2() { return 0; };
    virtual void obwod() {};
};

class Kwadrat :public Figura
{
public:
    int a;
    Kwadrat()
    {

        a = rand() % 10;

    }

    void pole()
    {

        cout << "Pole kwadratu: " << a*a << endl;

    }
    void obwod()
    {

        cout << "Obwod kwadratu: " <<4*a <<endl;


    }

    int pole2()
    {

        return a*a;

    }

};

class Kolo :public Figura
{
public:
    int r;

    Kolo()
    {

        r = rand() % 10;

    }

    void pole()
    {

        cout << "Pole kola: " << 3.14*r*r << endl;

    }
    void obwod()
    {

        cout << "Obwod kola: " << 2 * 3.14*r << endl;

    }


    int pole2()
    {

        return 3.14*r*r;
    }

};

class Prostokat :public Figura
{
public:
    int a, b;
    Prostokat()
    {

        a = rand() % 10;
        b = rand() % 10;

    }

    void pole()
    {

        cout << "Pole prostokata: " <<a*b<< endl;

    }
    void obwod()
    {

        cout << "Obwod prostokata: " << (2 * a) + (2 * b) << endl;

    }
    int pole2()
    {

        return a*b;
    }


};
int main()

{
    int suma=0;
    Figura *tmp, *H = NULL;
    srand(time(NULL));


    for (int i = 0; i < 20; i++)
    {

        switch (rand() % 3)
        {
        case 0:
            tmp = new Kwadrat();
            tmp->pole();
            tmp->obwod();
            break;
        case 1:
            tmp = new Kolo();
            tmp->pole();
            tmp->obwod();
            break;
        case 2:
            tmp = new Prostokat();
            tmp->pole();
            tmp->obwod();
            break;

        }
        cout << endl;

        tmp->next = H;
        H = tmp;

    }

    Figura *M = H;
    Figura *MM = H;

    while (M)
    {
        suma += (M->pole2());
        M = M->next;

    }
    cout << "SREDNIA: " << suma/20<< endl;


    system("pause");
    return 0;
}