diff --git a/a3/binary_search_tree.c b/a3/binary_search_tree.c
new file mode 100644
index 0000000..f5ff94e
--- /dev/null
+++ b/a3/binary_search_tree.c
@@ -0,0 +1,21 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include "binary_search_tree.h"
+
+node_t *build_tree(int *tree_data, size_t tree_data_len){
+
+    node_t *koren = (node_t *)malloc(sizeof(node_t));
+
+    if(tree_data == NULL || tree_data_len == NULL){
+        return 0;
+    }
+
+    if(tree_data != NULL && tree_data_len != NULL){
+        koren->data = tree_data[0];
+        koren->left = tree_data[0];
+    }
+
+    return koren;
+}
+