my %array1 = map {$_ => $_}(1,2,5,9,11,12,13);
my %array2 = map {$_ => $_}(1,2,5,11,12,13);
my %array3 = map {$_ => $_}(1,2,5,7,9,12,13);

my %all = map {$_=>$_} (keys %array1, keys %array2, keys %array3);

foreach (sort {$a <=> $b} keys %all)
{
	if (exists($array1{$_}) + exists($array2{$_}) + exists($array3{$_}) == 2)
	{
		print "$_\n";
	}
}