#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;
}
int StrToInt(string b)
{
    int l, M;
    l = b.length();
    M = 0;
    for (int i = 0; i < l; i++)
    {
        M += (b[i] - '0') * pow(10, l - i - 1);
    }
    return M;
}
struct stack {
    int data;
    struct stack* next;
};
void s_push(stack** top, int D) {
    stack* node;
    node = new stack();
    node->data = D;
    if (top == NULL) {
        *top = node;
    }
    else
    {
        node->next = *top;
        *top = node;
    }
}
void s_print(stack* top) {
     stack* node = top;
     if (top == NULL)
     {
         cout << "The stack is empty \n";
     }
     else
     {
         cout << "The stack consists : \n";
         while (node) {
             cout << node->data << " ";
             node = node->next;
         }
     }
}
void s_delete_key(stack** top,int p) {
    if (p <= 0)
    {
        cout << "You`re idiot!!! The stack is empty\n";
    }
    else
    {
        stack* node = *top;
        *top = node->next;
        free(node);
        node->data = NULL;
        node->next = NULL;
        cout << "The top element is deleted \n";
    }
}
int main()
{
    stack* top = NULL;
    char choice;
    string number;
    int num=0,p=0;
    do {
        metka:
        choice = menu();
        switch (choice)
        {
        case '1':
            cout << "Input an element :";
            cin >> number;
            for (auto c : number)
            {
                if (c >= '0' && c <= '9')
                {
                    num = StrToInt(number);
                }
                else
                    goto metka;
            }
            cout << endl;
            s_push(&top, num);
            cout << "The element is added \n";
            p++;
            break;
        case '2':
            s_delete_key(&top,p);
            p--;
            break;
        case '3':
            s_print(top);
            cout << endl;
            break;
        default: cout << "System exit\n";
        }
    } while (choice != '4');
}