Stack and Queue

#include <iostream>

using namespace std;

const int MAXINT = -2147483647;

struct slistEl
{
    slistEl *next;
    int data;
};

class stack
{
private: slistEl* S;
public:stack();
    ~stack();
    bool empty(void);
    slistEl* top(void);
    void push(int v);
    void pop(void);
};

stack::stack()
{
    S = NULL;
}

stack::~stack()
{
    while(S) pop();
}

bool stack::empty(void)
{
    return !S;
}

slistEl *stack::top(void)
{
    return S;
}

void stack::push(int v)
{
    slistEl* e = new slistEl;

    e->data= v;

    e->next= S;
    S = e;
}

void stack::pop(void)
{
    if(S)
    {
        slistEl* e = S;
        S = S->next;
        delete e;
    }
}


class queue
{
private:
    slistEl *head;
    slistEl *tail;

public:
    queue();
    ~queue();
    bool empty(void);
    int front(void);
    void push(int v);
    void pop(void);
};

queue::queue()
{
    head = tail = NULL;
}

queue::~queue()
{
    while(head) pop();
}

bool queue::empty(void)
{
    return !head;
}

int queue::front(void)
{
    if(head) return head -> data;
    else return -MAXINT;
}

void queue::push(int v)
{
    slistEl* p = new slistEl;
    p->next= NULL;
    p->data= v;
    if(tail) tail->next= p;
    else head= p;
    tail = p;
}

void queue::pop(void)
{
    if(head)
    {
        slistEl* p = head;
        head = head->next;
        if(!head) tail= NULL;
        delete p;
    }
}

int main()
{
    stack S;
    queue Q;

    int i,j;
    cout<< "Stos:" << endl;
    for(i = 1; i <= 10; i++) S.push(i);
    while(!S.empty())
    {
        cout<< S.top()->data << endl;
        S.pop();
    }
    cout<< "Kolejka:" << endl;
    for(j = 1; j <= 10; j++) Q.push(j);
    while(!Q.empty())
    {
        cout<< Q.front() << endl;
        Q.pop();
    }
}