#include <iostream>

using namespace std;

struct Node {
  char data;
  Node* next;
};

class Stack {
  public:
    Node* head;
    int size;
    void add(char value);
    void output();
    Stack();
    ~Stack();
};

int main() {
  Stack stack1;
  stack1.add('h');
  stack1.add('e');
  stack1.add('l');
  stack1.add('l');
  stack1.add('o');
  stack1.output();

  return 0;
}

Stack::Stack()
  :size(0) {}

Stack::~Stack() {
  Node* cursor = head;
  Node* next;

  while (cursor != NULL)
  {
    next = cursor->next;
    delete cursor;
    cursor = NULL;
    cursor = next;
  }
}

void Stack::add(char value) {
  if (size == 0) {
    head = new Node;
    head->data = value;
    head->next = NULL;
  } else {
    Node* ptr = new Node;
    ptr->data = value;
    ptr->next = head;
    head = ptr;
  }
  ++size;
}

void Stack::output()
{
  Node* cursor = head;
  while (cursor && cursor->next) {
    cout << cursor->data << endl;
    cursor = cursor->next;
  }
  if (cursor) { cout << cursor->data << endl; }
}