#include <iostream>

class Parent
{
protected:
    int my_num;
public:
    Parent(int my_num)
    {
        this->my_num = my_num;
    }
// virtual
    void eat()
    {
        std::cout << this->my_num << std::endl;
    }
};

class Child : Parent
{
public:
    Child(int my_num) : Parent(my_num)
    {

    }

    void eat()
    {
        std::cout << "child: " << this->my_num << std::endl;
    }
};

void dummy_fun(Parent* p)
{
    p->eat();
}

int main()
{
    Parent* p = new Parent(4);
    Child* c = new Child(5);

    dummy_fun(p);
    dummy_fun((Parent*) c);

    return 0;
}