diff --git a/lab12/4.c b/lab12/4.c
index 65b3dba..9e7e559 100644
--- a/lab12/4.c
+++ b/lab12/4.c
@@ -1 +1,72 @@
-// todo
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct _bst * Bnode;
+
+struct _bst {
+  Bnode left;
+  Bnode right;
+  float data;
+};
+
+Bnode root;
+
+Bnode init(float data) {
+  Bnode node = malloc(sizeof(struct _bst));
+  node->data = data;
+  node->left = NULL;
+  node->right = NULL;
+
+  return node;
+};
+
+void insert(Bnode node, float data) {
+  if (data >= node->data && node->right) {
+    insert(node->right, data);
+  } else if (data < node->data && node->left) {
+    insert(node->left, data);
+  } else {
+    Bnode temp = malloc(sizeof(struct _bst));
+    temp->data = data;
+    temp->left = NULL;
+    temp->right = NULL;
+    if (data > node->data) {
+      node->right = temp;
+    } else if (data < node->data) {
+      node->left= temp;
+    } else {
+      free(temp);
+      printf("%f is already in node!\n", data);
+    }
+  }
+}
+
+void print_tree(Bnode root) {
+  if (root) {
+    printf("%f - ", root->data);
+    if (root->right) {
+      printf(" R: %f ", root->right->data);
+    }
+    if (root->left) {
+      printf(" L: %f ", root->left->data);
+    }
+    printf("\n");
+  } else {
+    return;
+  }
+  print_tree(root->right);
+  print_tree(root->left);
+}
+
+int main() {
+  root = init(10);
+  insert(root, 5);
+  insert(root, 14.5);
+  insert(root, 13);
+  insert(root, 1);
+  insert(root, 1);
+  insert(root, 16);
+  insert(root, 19);
+  print_tree(root);
+  return 0;
+}