Drupal Side/Sub Menu code

Copy this code and paste it on block...

<?php
     $main = menu_navigation_links('main-menu', '1');
     echo theme('links__system_main_menu', array(
       'links' => $main,
       'attributes' => array(
         'id' => 'main-menu',
         'class' => 'active-trail'
       ),
     ));
?>