#include <iostream>  
  using namespace std;  
  #include <process.h>)  

  class Stack{  
     protected:                   
        enum { MAX = 3 };         
        int st[MAX];              
        int top;                  
     public:  
        Stack()                   
        { top = -1; }  
        void push(int var)        
        { st[++top] = var; }  
        int pop()                 
        { return st[top--]; }  
  };  
  class Stack2 : public Stack  
  {  
     public:  
        void push(int var)
        {  
           if(top >= MAX-1)
              { cout << "\nError: stack is full"; exit(1); }  
           Stack::push(var);
        }  
        int pop()           
           {  
           if(top < 0)      
              { cout << "\nError: stack is empty\n"; exit(1); }  
           return Stack::pop();     
           }  
  };  
  int main()  
  {  
     Stack2 s1;  
    
     s1.push(11);                   
     s1.push(22);  
     s1.push(33);  
    
     cout << endl << s1.pop();      
     cout << endl << s1.pop();  
     cout << endl << s1.pop();  
     cout << endl << s1.pop();        
     cout << endl;  
     return 0;  
  }