diff --git a/buggy.py b/buggy.py
--- a/buggy.py
+++ b/buggy.py
@@ -15,5 +15,5 @@
             if i % 2 == 0:
                 sum = sum + int(result[i])
             else:
-                sum = sum + int(result[i])
+                sum = sum - int(result[i])
         return sum
