Need help about path

My CI project
127.0.0.1/CI
The path is CI/
When URL 127.0.0.1/CI /show/1
The path is CI/show
but I want it still CI/
routes.php
$route['default_controller'] = 'welcome';
$route['wish/(:num)'] = 'welcome/wish/$1';
Welcome.php
class Welcome extends CI_Controller {
public function index()
{
$this->load->view('index.html');
}
public function show($a){
$this->load->helper('url');
$data['title'] = 'help';
$data['id'] = $a;
$this->load->view('page',$data);
}
}