Присутствуют ли ошибки в следующей программе?

class A {}; 
class B: A {}; 
struct C {}; 
struct D: C {}; 
 
int main(void) { 
  A *clA = new B();  //1 
  B *clB = new B();  //2 
  C *stC = new D();  //3 
  D *stD = new D();  //4 
 
  delete clA;  
  delete clB; 
  delete stC; 
  delete stD; 
 
  return 0; 
}