use strict;

my @a1 = ( 'x','y','z');
my @a2 = ('z','b','c');
my @combined = @a1;
push(@combined,$_) for @a2;
my %dupes;
$dupes{$_}++ for (sort @combined);
my @results = map{if($dupes{$_} > 1) { $_; }}keys %dupes;
print @results;