#include <iostream>
using namespace std ;

class A
{
	public:
	 int x1 ;
	 virtual void function1()
	  {
	  }
};

class B : public A
{
	public:
	 int x1B ;
};

class C : public A
{
	public:
	 int x1C ;

};

class D
{
};

class Person
{
   public:
	 virtual void function1()
	  {
	  }

};

class Employee : public Person
{
};


class Student : public  Person
{
};



int main()
{
	A* aObject = new B() ;
	//Should not be allowed.
    D* dObject = (D*)aObject ;

    dObject = dynamic_cast<D*> (aObject) ;
    if ( dObject == NULL )
      cout << "Invalid cast from A to D." << endl ;
    else
      cout << "Valid cast from A to D." << endl ;

    //Should not be allowed.
    C* cObject = (C*)aObject ;

    cObject = dynamic_cast<C*> (aObject) ;
    if ( cObject == NULL )
      cout << "Invalid cast from A to C." << endl ;
    else
      cout << "Valid cast from A to C." << endl ;


    B* bObject = (B*)aObject ;
    bObject = dynamic_cast<B*> (aObject) ;
    if ( bObject == NULL )
      cout << "Invalid cast from A to B." << endl ;
    else
      cout << "Valid cast from A to B." << endl ;


   Person* personObject = new Employee() ;
   Student* studentObject = (Student*)personObject ;

    studentObject = dynamic_cast<Student*> (personObject) ;
    if ( studentObject == NULL )
      cout << "Invalid cast from Person to Student." << endl ;
    else
      cout << "Valid cast from Person to Student." << endl ;



}