my @info = ();
while (my $entry = $dir->next) {
	if (-d $entry && $entry=~ m/qt_4/)
	{
		my $stat = $entry->stat or warn("$entry: $!\n"), next;
		push @info, $stat->mtime;		
	}
}
my @newdir = sort{$b<=>$a}(@info);
print "$newdir[0]\n";