diff --git a/trees_and_graphs/construct_tree_inorder_preorder.py b/trees_and_graphs/construct_tree_inorder_preorder.py
index efb6d04..765f32a 100644
--- a/trees_and_graphs/construct_tree_inorder_preorder.py
+++ b/trees_and_graphs/construct_tree_inorder_preorder.py
@@ -1,3 +1,7 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# author: bt3gl
+
 def build_tree(preorder: list[int], inorder: list[int]) -> Optional[TreeNode]:
         
         def helper(i_left, i_right, index_map):