diff --git a/a3/binary_search_tree.c b/a3/binary_search_tree.c
index 6f85c24..8ceecc1 100644
--- a/a3/binary_search_tree.c
+++ b/a3/binary_search_tree.c
@@ -2,6 +2,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include "binary_search_tree.h"
+
 node_t *build_tree(int *, size_t );
 void add_dereva(node_t* , int );
 void free_tree(node_t *);
@@ -17,6 +18,7 @@ node_t *build_tree(int *tree_data, size_t tree_data_len){
     for(unsigned int i=1; i<tree_data_len; i++){
          add_dereva( first, tree_data[i]);
     }
+    return first;
 }
 void add_dereva(node_t* first, int number){
     node_t* buffer=first;