diff --git a/python/remove_duplicates_from_sorted_array.py b/python/26_remove_duplicates_from_sorted_array.py
similarity index 100%
rename from python/remove_duplicates_from_sorted_array.py
rename to python/26_remove_duplicates_from_sorted_array.py
diff --git a/python/remove_element.py b/python/27_remove_element.py
similarity index 100%
rename from python/remove_element.py
rename to python/27_remove_element.py
diff --git a/python/28_find_the_index_of_the_first_occurrence_in_a_string b/python/28_find_the_index_of_the_first_occurrence_in_a_string
new file mode 100644
index 0000000..d843ed9
--- /dev/null
+++ b/python/28_find_the_index_of_the_first_occurrence_in_a_string
@@ -0,0 +1,6 @@
+class Solution:
+    def strStr(self, haystack: str, needle: str) -> int:
+        for i in range(len(haystack)):
+            if haystack[i:i+len(needle)] == needle:
+                return i
+        return -1
diff --git a/python/minimum_operations_to_exceed_threshold_value_i.py b/python/3065_minimum_operations_to_exceed_threshold_value_i.py
similarity index 100%
rename from python/minimum_operations_to_exceed_threshold_value_i.py
rename to python/3065_minimum_operations_to_exceed_threshold_value_i.py
diff --git a/python/minimum_operations_to_exceed_threshold_value_ii.py b/python/3066_minimum_operations_to_exceed_threshold_value_ii.py
similarity index 100%
rename from python/minimum_operations_to_exceed_threshold_value_ii.py
rename to python/3066_minimum_operations_to_exceed_threshold_value_ii.py