#include <iostream> 
#define SIZE 100 
using namespace std; 
class B; 
class A { 
    int items[SIZE]; 
    int sp; 
 
public: 
    friend class B; 
    B create() const; 
    A() { 
        sp = -1; 
    } 
    bool empty() 
    { 
        return (sp == -1); 
    } 
    void in(int in) 
    { 
        if (sp < SIZE - 1) 
            items[++sp] = in; 
        else 
            cout << "in: impossible to do" << endl;  // was: cout << "in:&#9251;impossible&#9251;to&#9251;do" << endl; 
    } 
    int out() 
    { 
        if (empty()) 
            cout << "out: impossible to do" << endl; // was: cout << "out:&#9251;impossible&#9251;to&#9251;do" << endl; 
        return items[sp--]; 
    } 
}; 
 
class B { 
    const A* a; // was const A&#8727; a 
    int index; 
 
public: 
    B(const A* s) {  // B(const A&#8727; s) {
        a = s; 
    } 
    void first() { 
        index = 0; 
    } 
    void next() { 
        index++; 
    } 
    bool done() { 
        return (index == a->sp + 1); 
    } 
    int item() { 
        return a->items[index]; 
    } 
}; 
 
B A::create() const 
{ 
    return *(new B(this)); // return &#8727;(new B(this)); 
}