Configuring routes for controllers/admin subfolder

[eluser]CARP[/eluser]
[quote author="clooner" date="1214337094"]Try to use "directory/controller/function" in the routing! So this could be "admin/admin/index"[/quote]

Hi
Didn't understand a word, I just only wanted to know what to put (apart from this line)
$route['default_controller'] = "principal";
in the config/routes.php file
so when visitors call /admin, a default controller gets called automatically (if possible)

Thanks