#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_K 100
#define L 100

static char *words[2 * MAX_K + 1];

static void read_words (int *n, int k, char **tgt)
{
  char buffer[L + 1];

  while (*n > 0 && k-- > 0)
    {
      scanf ("%s", buffer);
      tgt[k] = strdup (buffer);
      (*n)--;
    }
  while (k-- > 0)
    tgt[k] = NULL;
}

static int cmps (const void *a, const void *b)
{
  const char *sa = *(const char **) a;
  const char *sb = *(const char **) b;

  if (!sa)
    return 1;
  if (!sb)
    return -1;

  return strcmp (sa, sb);
}

int main(void)
{
  int n, k, i;

  scanf ("%d%d", &n, &k);

  read_words (&n, k, words + k);
  while (1)
    {
      read_words (&n, k, words);
      qsort (words, 2 * k, sizeof (char *), cmps);
      if (!n)
	break;
      for (i = 0; i < k; i++)
	{
	  puts (words[i]);
	  free (words[i]);
	}
    }
  for (i = 0; words[i]; i++)
    {
      puts (words[i]);
      free (words[i]);
    }

  return 0;
}