#include <iostream>
using namespace std;
char menu()
{
    char choice;
    cout << "Menu \n";
    cout << "1. Add an element \n";
    cout << "2. Remove an element \n";
    cout << "3. Show the stack \n";
    cout << "4. Exit\n";
    cin >> choice;
    return choice;
}
struct stack {
    int data;
    struct stack* next;
};
void s_push(stack** top, int D) {
    stack* q;
    q = new stack();
    q->data = D;
    if (top == NULL) {
        *top = q;
    }
    else
    {
        q->next = *top;
        *top = q;
    }
}
void s_print(stack* top) {
     stack* q = top;
     if (top == NULL)
     {
         cout << "The stack is empty \n";
     }
     else
     {
         cout << "The stack consists : \n";
         while (q) {
             cout << q->data << " ";
             q = q->next;
         }
     }
}
void s_delete_key(stack** top) {
    stack* q = *top;
    *top = q->next;
    free(q);
    q->data = NULL;
    q->next = NULL;
}
int main()
{
    stack* top = NULL;
    char choice;
    int number;
    do {
        choice = menu();
        switch (choice)
        {
        case '1':
            cout << "Input an element :";
            cin >> number;
            cout << endl;
            s_push(&top, number);
            break;
        case '2':
            s_delete_key(&top);
            cout << "The top element is deleted \n";
            break;
        case '3':
            s_print(top);
            cout << endl;
            break;
        default: cout << "System exit\n";
        }
    } while (choice != '4');
}