#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
#include <cmath>
#include <cassert>
#include <cctype>

using namespace std;

int random_in_range(int min, int max)
{ return random() % (max - min + 1) + min; }

string random_string(int min_length, int max_length)
{ string result;
  result += (char)random_in_range('A', 'Z');
  int len = random_in_range(min_length, max_length);
  for (int i = 1; i <len; i += 1)
    result += (char)random_in_range('a', 'z');
  return result; }

class list
{ protected:

    class link
    { public:
        string data;
        link * next;
        link(string d, link * n = NULL)
        { data = d;
          next = n; } };

    link * first, * last;

  public:

    class enumerator
    { protected:
        link * ptr;

      public:
        enumerator(link * x)
        { ptr = x; }
        
        bool any_more() const
        { return ptr != NULL; }
        
        string get_next()
        { if (ptr == NULL)
            throw runtime_error("get_next on empty enumerator");
          string result = ptr->data;
          ptr = ptr->next;
          return result; } };

    list()
    { first = NULL;
      last = NULL; }

    void clear()
    { while (first != NULL)
      { link * next = first->next;
        delete first;
        first = next; }
      last = NULL; }

    ~list()
    { clear(); }

    bool empty() const
    { return first == NULL; }

    enumerator get_enumerator() const
    { return enumerator(first); }

    void add_to_front(string s)
    { if (first == NULL)
      { first = new link(s);
        last = first; }
      else
        first = new link(s, first); }

    void add_to_end(string s)
    { if (first == NULL)
      { first = new link(s);
        last = first; }
      else
      { last->next = new link(s);
        last = last->next; } }

    string see_first() const
    { if (first == NULL)
        throw runtime_error("see_first on empty list");
      return first->data; }

    string remove_first()
    { if (first == NULL)
        throw runtime_error("remove_first on empty list");
      link * old = first;
      first = first->next;
      string result = old->data;
      delete old;
      return result; } };

int main(int argc, char * argv[])
{ int number = 16;
  if (argc > 1)
    number = atol(argv[1]);
  srandomdev();
  
  list a;
  for (int i = 0; i < number; i += 1)
    a.add_to_end(random_string(5, 7));

  list::enumerator e = a.get_enumerator();
  while (e.any_more())
    cout << e.get_next() << "\n"; }