#include <iostream>

using namespace std;

class Document
{
public:
  Document ( void ) : docid ( 0 )
  {
  }
  int get_docid ( void );
private:
  int docid;
};
int Document::get_docid ( void )
{
  return docid;
}

class Book : public Document
{
public:
  Book ( void ) : Document ( ), bookid ( 0 )
  {
  }
  int get_bookid ( void );
private:
  int bookid;
};
int Book::get_bookid ( void )
{
  return bookid;
}

int main ( void )
{
  Book mybook;

  try
  {
    throw mybook;
  }
  catch ( Document &d )                //违背1
  {
    cout << d.get_docid ( ) << endl;
  } 
  catch ( Book &b )                    //违背2
  {
    cout << b.get_bookid ( ) << endl;
  }

  return ( 0 );
}