#include <iostream>

using namespace std;

struct A
{
    virtual ~A() = default; // required
    virtual void a() { cout << "AA"; }
    virtual void b() { cout << "AB"; }
    virtual void c() { cout << "AC"; }
};

struct B : public A
{
    void a() { cout << "BA"; }
    void b() { cout << "BB"; }
    void c() { cout << "BC"; }
};

struct C : public A
{
    void a() override { cout << "CA"; }
    void b() override { cout << "CB"; }
    void c() override { cout << "CC"; }
};

int main()
{
    A *a = new A();
    a->a();
    a->b();
    a->c();
    cout << endl;
    delete a;

    A *b = new B();
    b->a();
    b->b();
    b->c();
    cout << endl;
    delete b;

    A *c = new C();
    c->a();
    c->b();
    c->c();
    cout << endl;
    delete c;

    return 0;
}