my %folders = (
    4464 => 'foldername_1',
    4465 => 'foldername_2',
    4466 => 'foldername_3',
);

my @subfolders = split /\n/, <<'SUBFOLDER_LIST';
Folder 1298 - foldername_ten.
   subfolder 1299.
   subfolder 1300.
Folder 1299 - foldername_eleven.
   No sub folders.
Folder 1300 - foldername_twelve.
   No sub folders.
Folder 1311 - foldername_thirteen.
   subfolder 1317.
   subfolder 1318.
   subfolder 1958.
SUBFOLDER_LIST
    ;