diff --git a/extra/distract-the-trainers/solution.py b/extra/distract-the-trainers/solution.py
index a3f3918..0d12d81 100644
--- a/extra/distract-the-trainers/solution.py
+++ b/extra/distract-the-trainers/solution.py
@@ -24,6 +24,8 @@ def generate_trainer_pairs(trainer_id_list):
                 yield [(first_id, second_id)] + pairs
 
 def check_loop(x, y):
+    if (x + y) % 2 == 1: # sum is odd
+        return True
     a, b = x, y
     memo = []
     while a != b:
@@ -38,6 +40,7 @@ def check_loop(x, y):
     return False
 
 tests = [
+        ([1], 1),
         ([1, 1], 2),
         ([1, 7, 3, 21, 13, 19], 0),
         ]