char *literals(char *s) {
  char array[10];
  int elements = 0;
  while (*s != '\0') {
    char c = *s;
    s++;

    if (c != 'V' && c != 'v' && isalpha(c) != 0) {
      if (check_existing(c, array, elements) == 0) {
        array[elements] = c;
        elements++;
      }
    }
  }

  char *literals;
  literals = malloc(elements);
  int i;
  for(i = 0; i < elements; i++) {
    literals[i] = array[i];
  }
  return literals;
}