#include <iostream.h>
#include <vector>

using namespace std;

class BV            { public: virtual void f(){cout <<"BB"; } };
class D1V: public BV{ public: void f(){cout <<"D1"; } };
class D2V: public BV{ public: void f(){cout <<"D2"; } };
 
int main(){
	vector <BV*> a;
	a.push_back(new D1V);
	a.push_back(new D2V);
	a.push_back(new D2V);
	a.push_back(new D1V);
      for( int i = 0; i < a.size(); ++i)
	      a[i] -> f();
}//end main