CI 分页“第一页”问题

routes.php中

$route['i/p/(:num)'] = "welcome/index";
$route['i/p'] 　　　　= "welcome/index/1";

welcome.php中

$page 　　　　= $this->uri->segment($config['uri_segment']);
$page 　　　　= $page?$page-1:0;
$down_latest = $this->ma->get_category_latest($config['per_page'],$page); 

URL中

http://xxx.com/i/p/544
http://xxx.com/i/p/1
http://xxx.com/i/p/