diff --git a/lc28. Implement strStr().py b/lc28. Implement strStr().py
index f8d6b5c..7c5799c 100644
--- a/lc28. Implement strStr().py	
+++ b/lc28. Implement strStr().py	
@@ -5,7 +5,10 @@ def strStr(self, haystack, needle):
         :type needle: str
         :rtype: int
         """
-        return haystack.find(needle)
+        for i in range(len(haystack) - len(needle) + 1):
+            if haystack[i:i + len(needle)] == needle:
+                return i
+        return -1
 
 
 haystack = "hello"