int g;
class A {
  public:
  A(int i){g=i;};
  private:
  A();
};

class B: A {
  public:
  typedef A base_type;
  typedef B this_type;
  B():base_type(10) {}
  B(const this_type& b): A(20) {g++;}
};

class C: B
{
  typedef B base_type;
  typedef C this_type;
  public:
  C(): base_type() {}
  C(const base_type& b): base_type(b){g++;}
};


C c;

int main()
{
  assert(g==10);
  B b;
  C c2 = b;
  assert(g==22);
}
