diff --git a/ea/Ub4/a12.py b/ea/Ub4/a12.py
old mode 100644
new mode 100755
index f53af5a..8a52536
--- a/ea/Ub4/a12.py
+++ b/ea/Ub4/a12.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 import numpy as np
 import matplotlib.pyplot as plt
 import copy as cp