diff --git a/cgi-bin/vorbereitung/api.php b/cgi-bin/vorbereitung/api.php
index d8a6e99..7ddd674 100644
--- a/cgi-bin/vorbereitung/api.php
+++ b/cgi-bin/vorbereitung/api.php
@@ -1,6 +1,9 @@
 <?php
 
-$n = $_REQUEST['n'];
+$n = 0;
+if (isset($_REQUEST['n'])) {
+        $n = $_REQUEST['n'];
+} 
 
 header("Content-Type: application/json");