diff --git a/lab04/pom.xml b/lab04/pom.xml
new file mode 100644
index 0000000..35fab1c
--- /dev/null
+++ b/lab04/pom.xml
@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.example</groupId>
+    <artifactId>lab04</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <properties>
+        <maven.compiler.source>8</maven.compiler.source>
+        <maven.compiler.target>8</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>RELEASE</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>RELEASE</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>
\ No newline at end of file
diff --git a/lab04/src/main/java/org/example/BSTNode.java b/lab04/src/main/java/org/example/BSTNode.java
new file mode 100644
index 0000000..3578538
--- /dev/null
+++ b/lab04/src/main/java/org/example/BSTNode.java
@@ -0,0 +1,114 @@
+package org.example;
+
+public class BSTNode {
+    private Node root;
+    private class Node {
+        private int key;
+        private String val;
+        private Node left,right;
+        private int size;
+
+        public Node(int key, String val, int initSize) {
+            this.key = key;
+            this.val = val;
+            size = initSize;
+        }
+    }
+
+    public int getSize() {
+        return getSize(root);
+    }
+    private int getSize(Node node) {
+        if(node == null)
+            return 0;
+        else
+            return node.size;
+    }
+
+    public void insertValue(int key, String val) {
+        root = insertValue(root, key, val);
+    }
+    private Node insertValue(Node node, int key, String val) {
+        if (node == null) {
+            return new Node(key,val,1);
+        }
+
+        if (key > node.key) {
+            node.right = insertValue(node.right,key,val);
+        } else if (key < node.key) {
+            node.left = insertValue(node.left,key,val);
+        } else {
+            node.val = val;
+        }
+
+        node.size = getSize(node.left) + getSize(node.right) + 1;
+
+        return node;
+    }
+
+    public void deleteValue(int key) {
+        root = deleteValue(root, key);
+    }
+    private Node deleteValue(Node node, int key) {
+        if (node == null) return null;
+
+        if (key > node.key) node.right = deleteValue(node.right, key);
+        else if (key < node.key) node.left = deleteValue(node.left, key);
+        else {
+            if (node.right == null) return node.left;
+            else if (node.left == null) return node.right;
+
+            root.key = minValue(root.right);
+
+            root.right = deleteValue(root.right, root.key);
+        }
+
+        node.size = getSize(node.left) + getSize(node.right) + 1;
+
+        return node;
+    }
+
+    private int minValue(Node node) {
+        int minValue = node.key;
+        while (node.left != null) {
+            minValue = node.left.key;
+            node = node.left;
+        }
+
+        return minValue;
+    }
+
+    public String searchValue(int key){
+        return searchValue(root, key);
+    }
+    private String searchValue (Node root, int key)
+    {
+        if (root == null) {
+            return null;
+        }
+
+        if (key == root.key){
+            return root.val;
+        }
+
+        if (key > root.key)
+            return searchValue(root.right, key);
+
+        return searchValue(root.left, key);
+    }
+
+    public void depthOrderTraversal() {
+        depthTraversal(root);
+    }
+
+    private void depthTraversal(Node node) {
+        if (node != null) {
+            System.out.print("Key: " + node.key + " Value: " + node.val + "\n");
+            depthTraversal(node.left);
+            depthTraversal(node.right);
+        }
+    }
+
+
+}
+
diff --git a/lab04/src/test/java/org/example/BSTTest.java b/lab04/src/test/java/org/example/BSTTest.java
new file mode 100644
index 0000000..70ed4a9
--- /dev/null
+++ b/lab04/src/test/java/org/example/BSTTest.java
@@ -0,0 +1,110 @@
+package org.example;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import org.junit.jupiter.api.Test;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class BSTTest {
+    Map<Integer,String> tree;
+
+    @BeforeEach
+    void treeInit() {
+        tree = new HashMap<>();
+
+        tree.put(11,"Одинадцять");
+        tree.put(19,"Дев'ятнадцять");
+        tree.put(15,"П'ятнадцять");
+        tree.put(25,"Двадцять п'ять");
+        tree.put(12,"Дванадцять");
+        tree.put(13,"Тринадцять");
+        tree.put(16,"Шістнадцять");
+        tree.put(7,"Сім");
+        tree.put(24,"Двадцять чотири");
+        tree.put(20,"Двадцять");
+        tree.put(10,"Десять");
+        tree.put(21,"Двадцять один");
+        tree.put(8,"Вісім");
+        tree.put(17,"Сімнадцять");
+        tree.put(18,"Вісімнадцять");
+        tree.put(9,"Дев'ять");
+        tree.put(26,"Двадцять шість");
+        tree.put(23,"Двадцять три");
+        tree.put(14,"Чотирнадцять");
+        tree.put(22,"Двадцять два");
+    }
+
+    private BSTNode mapTransferBstnode() {
+        BSTNode node = new BSTNode();
+
+        for (Map.Entry<Integer,String> item: tree.entrySet()) {
+            node.insertValue(item.getKey(), item.getValue());
+        }
+        return node;
+    }
+
+    @Test
+    void Test1() {
+        BSTNode node = mapTransferBstnode();
+
+        Assertions.assertEquals(20,tree.size());
+    }
+
+    @Test
+    void Test2() {
+        BSTNode node = mapTransferBstnode();
+
+        node.depthOrderTraversal();
+        System.out.println();
+        Assertions.assertEquals(20,tree.size());
+    }
+
+    @Test
+    void Test3() {
+        BSTNode node = mapTransferBstnode();
+
+        Assertions.assertEquals("Двадцять один",node.searchValue(21));
+        Assertions.assertNull(node.searchValue(90));
+        Assertions.assertEquals("Дев'ятнадцять",node.searchValue(19));
+        Assertions.assertNull(node.searchValue(45));
+    }
+
+    @Test
+    void Test4() {
+        BSTNode node = new BSTNode();
+
+        for (Map.Entry<Integer,String> item: tree.entrySet()) {
+            if(item.getKey()!=20) {
+                node.insertValue(item.getKey(), item.getValue());
+            }
+        }
+
+
+        node.insertValue(20,"Двадцять");
+
+        System.out.println(node.searchValue(20));
+        Assertions.assertEquals("Двадцять",node.searchValue(20));
+        node.insertValue(20,"Інше двадцять");
+
+        node.depthOrderTraversal();
+        System.out.println();
+        Assertions.assertEquals(20, node.getSize());
+
+        System.out.println(node.searchValue(20));
+        Assertions.assertEquals("Інше двадцять",node.searchValue(20));
+    }
+    @Test
+    void Test5() {
+        BSTNode node = mapTransferBstnode();
+
+        node.deleteValue(14);
+
+        node.depthOrderTraversal();
+        System.out.println();
+        Assertions.assertEquals(19, node.getSize());
+        Assertions.assertNull(node.searchValue(14));
+    }
+}
\ No newline at end of file
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diff --git a/lab04/target/classes/org/example/Main.class b/lab04/target/classes/org/example/Main.class
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