Activation Routes

[eluser]xtremer360[/eluser]
After a user registers on my site they are sent an email containing a link to my activation controller. The link comprises of the siteurl.com/activation/$user_id/$activation_key. I'm trying to figure out if these are the proper routes I need for the activation page. I also included what the index function line starts with?

Code:

$route['activation/(:num)/(:any)'] = 'activation/index/$1/$2';
$route['activation/(:num)'] = 'activation/index/$1';
$route['activation'] = 'activation';

Code:

public function index( $user_id = NULL, $registration_key = NULL )