my @dirs = (
    dir_tree( 'AB', 6, 1, 2 ),
    dir_tree( 'BC', 6, 1, 2 ),
);

my @subdirs = (
   dir_tree( 'F', 6, 1, 5 ),
);


for my $dir (@dirs) {
    for my $subdir (@subdirs) {
        print "/results/$dir/$subdir \n";
    }
}