Just to show another slightly different approach:

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;
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Will print out 'z' as the final result. map is a VERY useful function. But, like the manpage says, please don't make map go through all the work to produce an array (it's return value) and then discard it (unless you are playing a game of Perl-golf... Then all bets are off... ^_~).

Theodore Charles III
Network Administrator
Los Angeles Senior High
4650 W. Olympic Blvd.
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323-937-3210 ext. 224
email->secon_kun@hotmail.com
perl -e "map{print++$_}split//,Mdbnr;"