foreach(1..4) {
   my (%union, %intersect);
   foreach my $e (@title1, @{"title$_"}) {
      $union{$e}++ && $intersect{$e}++
    }
    my @intersect = sort keys %intersect;
    print FILEOUT "@intersect\n";
    print FILEOUT scalar @intersect;
    print FILEOUT "\n";
}