Select Code to Download

use strict;
use warnings;

...
my @intersect = sort keys %intersect;
print FILEOUT "@intersect\n"; #prints intersecting words
print FILEOUT scalar @intersect;

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

       array1 : array2 : array3 : array4
array1: 10 : 5 : 17 : 2
array2: 5 : 15 : 8 : 1
array3: 17 : 8 : 14 : 6
array4: 2 : 1 : 6 : 19