my @files_exist = reverse sort  map { $_ =~ s/^(\d+)\.html$/$1/; $_} 
     grep { /^\d+.\.html$/} readdir DIRE;


closedir DIRE;

my $how_many_page = sub { 
                      my ($how) = @_;
                      $how = $how/5;
                      $how =~ /(\d+?).?(\d+)?/;
                      if(!$2) { return $1 } else { return $1+1 }
                     };    

my $file = sub {
  my $file_name = shift;
  my($topic,$title,$lang);
  open my $FH,'<', '/home/lenn287/public_html/diary/'.$file_name.".html";
  while(<$FH>) {
    $topic = $1 if /<!--topic:(.+?)-->/;
    $title = $1 if /<!--title:(.+?)-->/;
    $lang = $1 if /<!--lang:(.+?)-->/;
  }
  close $FH;
  return ($topic,br(),$title,br(),$lang,p());
};
if($page !~ /^[0-$how_many_page->($#files_exist)]$/) {
  print header,start_html,"invalid $page",end_html;
  exit(0);
} 

my ($next,$previous);
if($page < $how_many_page->($#files_exist)) {
  my $next_page=$page+1;
  $next = a({href=>"/cgi-bin/author.pl?page=$next_page"},"next"); 
} else {
  $next='';
}

if($page > 0) {
  my $previous_page=$page-1;
  $previous = a({href=>"/cgi-bin/author.pl?page=$previous_page"},"previous"); 
} else {
  $previous='';
}

my $first_file = $page*5;
my $last_file = $page*5+4;
my @FILES;