diff --git a/TaskB04/run b/TaskB04/run
index 6f6bff5..9a9b847 100644
--- a/TaskB04/run
+++ b/TaskB04/run
@@ -44,7 +44,7 @@ auto = automata()
 for line in sys.stdin:
     auto.add_node(line)
 
-f = open(sys.argv[1].replace('.in', '.exp'), 'r')
+f = open(sys.argv[1].replace('.arg', '.exp'), 'r')
 
 for line in f:
     print(line)