use strict;

my %hash;

my @ary1 = qw(1 2 3 4 5);
my @ary2 = qw(6 7 8 1 2);

foreach (@ary1, @ary2){
	$hash{$_}++;
}
	
foreach my $key (keys %hash){
	print "$key showed up $hash{$key} times\n" if $hash{$key} != 1;
}