#include<iostream>
    #include<cstdio>
    #include<iomanip>
    #include<cassert>
    #include<string>
    #include<cmath>
    #include<iostream>
    #include<cmath>
    #include<sstream>
    #include<stdio.h>
    #include<stdlib.h>
     using namespace std;

  struct stack
   {
    int item;
    stack*link;
   };

  void push(stack*&s,int newitem) // pushes newitem onto s
   {
    stack*temp = new stack;
    cout << "push " << newitem << endl;
    temp->item = newitem;
    temp->link = s;
    s = temp;
   }

  bool empty(stack*s) // returns true if s is empty, false otherwise
   {
    return s == nullptr;
   }

  int pop(stack*&s) // returns and deletes most recently inserted item
   {
    assert(not empty(s)); // error if you try to pop an empty stack
    int rslt = s->item;
    s = s->link; // memory leak
    return rslt;
   }

  int main()
   {
    stack*s = NULL;
    if(empty(s)) cout << "s is empty "; else cout << "s is not empty ";
    cout << endl;
    push(s,5);
    if(empty(s)) cout << "s is empty "; else cout << "s is not empty ";
    cout << endl;
    push(s,3);
    cout << pop(s) << endl; 
    if(empty(s)) cout << "s is empty"; else cout << "s is not empty ";
    cout << endl;
    push(s,9);
    push(s,2);
    while (not empty(s)) cout << pop(s) << endl;
    if(empty(s)) cout << "s is empty "; else cout << "s is not empty ";
     cout << endl;
    return 1;
   }