diff --git a/09/09-2a.py b/09/09-2a.py
index 65cd3df..dd652d0 100644
--- a/09/09-2a.py
+++ b/09/09-2a.py
@@ -5,10 +5,10 @@ data = [[int(i) for i in line.strip().split()]for line in input_file]
 input_file.close()
 
 
-def find_diff(val_list):
+def find_prev(val_list):
     if val_list.count(0) == len(val_list):
         return 0
-    return val_list[0]-find_diff([(val_list[i+1]-val_list[i]) for i in range(len(val_list)-1)])
+    return val_list[0]-find_prev([(val_list[i + 1] - val_list[i]) for i in range(len(val_list) - 1)])
 
 
-print("Lösung:", sum([find_diff(d) for d in data]))
+print("Lösung:", sum([find_prev(d) for d in data]))