Stack using Linked List

//constructor, push, pop, isEmpty, getNumberOfElements, displayData, deleteStack, destructor
#include <iostream>
using namespace std;

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

class LinkedStack
{
    node *top;
public:
    LinkedStack()
    {
        top = NULL;
    }
    void push(int data)
    {
        node *item = new node;
        item->data = data;
        item->next = top;
        top = item;
    }
    bool isEmpty ()
    {
        return top == NULL;
    }
    int pop()
    {
        if (isEmpty())
        {
            cout << "Stack is empty!\n";
            return -1;
        }
        node *temp = top;
        int tempData = temp->data;
        top = top->next;
        delete temp;
        return tempData;
    }
    int getNumberOfElements()
    {
        int counter = 0;
        node *temp;
        for (temp = top ; temp != NULL ; temp = temp->next)
            counter++;
        return counter;
    }
    void displayStack()
    {
        node *temp;
        for (temp = top ; temp != NULL ; temp = temp->next)
            cout << temp->data << "\t";
    }
    void deleteStack()
    {
        node *temp;
        while (top != NULL)
        {
            temp = top;
            top = top->next;
            delete temp;
        }
    }
    ~LinkedStack()
    {
        deleteStack();
        cout << "\nStack is deleted!";
    }
};

int main()
{
    LinkedStack stack1;
    for (int k = 2 ; k <= 16 ; k*=2)
        stack1.push(k);
    stack1.displayStack();
    cout << endl;
    cout << stack1.getNumberOfElements() << endl;
    cout << stack1.pop() << "\t" << stack1.pop() << endl;
    stack1.displayStack();
    cout << endl;
    cout << stack1.getNumberOfElements() << endl;
}