diff --git a/a3/binary_search_tree.c b/a3/binary_search_tree.c
index 3a28213..8e8cd9d 100644
--- a/a3/binary_search_tree.c
+++ b/a3/binary_search_tree.c
@@ -1,6 +1,27 @@
 #include "binary_search_tree.h"
 #include <stdlib.h>
+#ifndef BINARY_SEARCH_TREE_H
+#define BINARY_SEARCH_TREE_H
+#include <stddef.h>
 
+typedef struct node node_t;
+
+struct node {
+    node_t *right;
+    node_t *left;
+    int data;
+};
+
+node_t *build_tree(int *tree_data, size_t tree_data_len);
+void free_tree(node_t *tree);
+int *sorted_data(node_t *tree);
+
+#endif
+
+// Deklarace proměnné sorted_index
+static int sorted_index;
+
+// Deklarace funkce insert
 node_t* insert(node_t *node, int data) {
     if (node == NULL) {
         node_t *new_node = (node_t*)malloc(sizeof(node_t));
@@ -16,6 +37,7 @@ node_t* insert(node_t *node, int data) {
     }
 }
 
+// Deklarace funkce inorder_traversal
 void inorder_traversal(node_t *node, int *sorted) {
     if (node == NULL) return;
     inorder_traversal(node->left, sorted);
@@ -23,6 +45,7 @@ void inorder_traversal(node_t *node, int *sorted) {
     inorder_traversal(node->right, sorted);
 }
 
+// Deklarace funkce build_tree
 node_t* build_tree(int *tree_data, size_t tree_data_len) {
     node_t *root = NULL;
     for (size_t i = 0; i < tree_data_len; i++) {
@@ -31,6 +54,7 @@ node_t* build_tree(int *tree_data, size_t tree_data_len) {
     return root;
 }
 
+// Deklarace funkce free_tree
 void free_tree(node_t *tree) {
     if (tree == NULL) return;
     free_tree(tree->left);
@@ -38,6 +62,7 @@ void free_tree(node_t *tree) {
     free(tree);
 }
 
+// Deklarace funkce sorted_data
 int *sorted_data(node_t *tree) {
     int *sorted = (int*)malloc(sizeof(int) * 1000); // Předpokládáme, že strom má maximálně 1000 prvků
     sorted_index = 0;