#include <iostream>
#include <vector>

class Base {
public:
  virtual void
  f()
  {
      std::cout << "Base\n";
  }
};

class Derived: public Base {
public:
  virtual void
  f()
  {
      std::cout << "Derived\n";
  }
};

int
main()
{
  std::vector<Base> s;
  Base a;
  s.push_back(a);
  Derived b;
  s.push_back(b);
  for (std::vector<Base>::iterator it = s.begin(); it != s.end(); ++it)
    it->f();

  return 0;
}