text: #include "common.h"
  
  class A {
  public:
      void PrintA1() {
          cout << "A" << endl;
      }
  
      virtual void PrintA2() {
          cout << "A" << endl;
      }
  };
  
  class B {
  public:
      void PrintB1() {
          cout << "B" << endl;
      }
  
      virtual void PrintB2() {
          cout << "B" << endl;
      }
  };
  
  int main() {
      A *pa = new A();
      B *pb = (B *) pa;
      pb->PrintB1();
      pb->PrintB2();
      return 0;
  }