diff --git a/leetcode/202.py b/leetcode/202.py
index 50d57c1..61773b6 100644
--- a/leetcode/202.py
+++ b/leetcode/202.py
@@ -4,11 +4,14 @@
 
 
 class Solution:
-    def isHappy(self, n: int, status: list = []) -> bool:
+    def isHappy(self, n: int, status=None) -> bool:
+        if status is None:
+            status = []
+
         str_n = str(n)
         total = 0
         for number in str_n:
-            total += int(number) * int(number)
+            total += int(number) ** 2
         if total == 1:
             return True
         if str(total) in status:
@@ -19,5 +22,5 @@ class Solution:
 
 
 if __name__ == "__main__":
-    number = 19
-    print(Solution().isHappy(19))
+    number = 13
+    print(Solution().isHappy(number))