// Node for singly linked list
//
// #ifndef NODE_H_
// #define NODE_H_

class Node
{
 friend class LL; // so LL can access the private data

 private: long data; Node *next;

 public: Node( long d = 0, Node *n = nullptr) { data = d; next = n; }

};

// #endif // NODE_H_
// singly linked list
//
// #ifndef LL_H_
// #define LL_H_

// #include "Node.h"

class LL
{
 private: Node *head, *tail;

 public: LL() { head = tail = nullptr; }

  bool empty() const; // true if list is empty, otherwise false

  void push_front( long d); // insert in front of head
  void push_back( long d);  // insert after tail

  long pop_front();         // remove from head
  long pop_back();          // remove from tail

  void reverse(); // put list in reverse order

  void print() const; // print the list
};

// #endif // LL_H_
// singly linked list
//
#include <iostream>
// #include "LL.h"
using namespace std;

void LL::push_front( long d)
{

}

void LL::push_back( long d)
{

}

void LL::print() const
{

}

#include <iostream>
// #include "LL.h"
using namespace std;

int main()
{
  LL list;

 // testing...
 //
  long a[] = { 1, 2, 3, -1 };

  for( int i = 0; a[i] > 0; ++i) list.push_front(a[i]);

  list.print();
}