#include <iostream>

class Mammal
{
public:
    Mammal():age(1) { std::cout << "Mammal constructor ...\n"; }
    virtual ~Mammal() { std::cout << "Mammal destructor ...\n"; }
    virtual void speak() const { std::cout << "Mammal speak!\n"; }
protected:
    int age;
};

class Cat : public Mammal
{
public:
    Cat() { std::cout << "Cat constructor ...\n"; }
    ~Cat() { std::cout << "Cat destructor ...\n"; }
    void speak() const { std::cout << "Meow!\n"; }
};

int main()
{
    Mammal *pCat = new Cat;
    pCat->speak();
    return 0;
}