diff --git a/src/tiaz0128/ch_08/solution_020.py b/src/tiaz0128/ch_08/solution_020.py
index 479a20f..0739841 100644
--- a/src/tiaz0128/ch_08/solution_020.py
+++ b/src/tiaz0128/ch_08/solution_020.py
@@ -1,2 +1,5 @@
+from collections import Counter
+
+
 def solution(participant, completion):
-    return
+    return list(Counter(participant) - Counter(completion))[0]