diff --git a/day12.py b/day12.py
index 05c8ed5..57208ef 100644
--- a/day12.py
+++ b/day12.py
@@ -1,9 +1,12 @@
 #!/usr/bin/env python3
 
 from itertools import combinations
-from math import lcm
+from math import gcd
 from functools import reduce
 
+def lcm(a, b):
+    return (a * b) // gcd(a, b)
+
 def comp(a, b):
     def f(arg):
         x, y = arg