require_once $CFG->dirroot.'/grade/lib.php';
require_once $CFG->dirroot.'/grade/report/grader/lib.php';
-$courseid = required_param('id'); // course id
+$courseid = required_param('id', PARAM_INT); // course id
$page = optional_param('page', 0, PARAM_INT); // active page
$perpageurl = optional_param('perpage', 0, PARAM_INT);
$edit = optional_param('edit', -1, PARAM_BOOL); // sticky editting mode