#ifndef _STACK_H_
#define _STACK_H_

#include <string>

using data_t = std::string;

// you must correct the stack to store integers
class Stack
{
public:
  Stack();
  ~Stack();
  Stack(Stack const&);
  Stack& operator=(Stack const&);
  bool isEmpty() const;

  void push(std::string const&);
  std::string pop();
  std::string& top();
  std::string const& top() const;

private:
  
  class Element
  {
  public:
    Element(std::string const&, Element* n = nullptr);
    Element(Element const&) = delete;
    ~Element();
    Element& operator=(Element const&) = delete;
    static Element* clone(Element const*);
    
    Element* next;
    std::string data;
  };
  
  Element* mtop;
};

#endif