#include <iostream>

using namespace std;

class A {
  public:
    void m1() { cout << "a1" << endl; }
    virtual void m2() { cout << "a2" << endl; }
};
class B : public A {
  public:
    void m1() { cout << "b1" << endl; }
    void m2() { cout << "b2" << endl; }
};

int main() {
  B* b = new B();
  A* a = b;

  a->m1();       
  a->m2();     
  b->m1();
  b->m2();
}