diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ead0ef36a..282f50ac5 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -8,10 +8,10 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
-      - name: Set up JDK 11
+      - name: Set up JDK 17
         uses: actions/setup-java@v2
         with:
-          java-version: '11'
+          java-version: '17'
           distribution: 'adopt'
           cache: maven
       - name: Build with Maven
diff --git a/src/main/java/core/basesyntax/Bulldozer.java b/src/main/java/core/basesyntax/Bulldozer.java
new file mode 100644
index 000000000..9646b3b63
--- /dev/null
+++ b/src/main/java/core/basesyntax/Bulldozer.java
@@ -0,0 +1,13 @@
+package core.basesyntax;
+
+public class Bulldozer extends Machine {
+    @Override
+    public void doWork() {
+        System.out.println("Bulldozer started its work");
+    }
+
+    @Override
+    public void stopWork() {
+        System.out.println("Bulldozer started its work");
+    }
+}
diff --git a/src/main/java/core/basesyntax/Excavator.java b/src/main/java/core/basesyntax/Excavator.java
new file mode 100644
index 000000000..6c52aa1ba
--- /dev/null
+++ b/src/main/java/core/basesyntax/Excavator.java
@@ -0,0 +1,14 @@
+package core.basesyntax;
+
+public class Excavator extends Machine {
+    @Override
+    public void doWork() {
+        System.out.println("Excavator started its work");
+    }
+
+    @Override
+    public void stopWork() {
+        System.out.println("Excavator stopped its work");
+    }
+}
+
diff --git a/src/main/java/core/basesyntax/Machine.java b/src/main/java/core/basesyntax/Machine.java
new file mode 100644
index 000000000..8f60ccf51
--- /dev/null
+++ b/src/main/java/core/basesyntax/Machine.java
@@ -0,0 +1,8 @@
+package core.basesyntax;
+
+public abstract class Machine {
+    public abstract void doWork();
+
+    public abstract void stopWork();
+}
+
diff --git a/src/main/java/core/basesyntax/MainApp.java b/src/main/java/core/basesyntax/MainApp.java
index f99e9a019..78163e059 100644
--- a/src/main/java/core/basesyntax/MainApp.java
+++ b/src/main/java/core/basesyntax/MainApp.java
@@ -1,5 +1,14 @@
 package core.basesyntax;
 
 public class MainApp {
-
+    public static void main(String[] args) {
+        Machine truck = new Truck();
+        Machine bulldozer = new Bulldozer();
+        Machine excavator = new Excavator();
+        Machine [] machines = new Machine[] {truck,bulldozer,excavator};
+        for (Machine machine:machines) {
+            machine.doWork();
+            machine.stopWork();
+        }
+    }
 }
diff --git a/src/main/java/core/basesyntax/Truck.java b/src/main/java/core/basesyntax/Truck.java
new file mode 100644
index 000000000..0df9fc7fd
--- /dev/null
+++ b/src/main/java/core/basesyntax/Truck.java
@@ -0,0 +1,13 @@
+package core.basesyntax;
+
+public class Truck extends Machine {
+    @Override
+    public void doWork() {
+        System.out.println("Truck started its work");
+    }
+
+    @Override
+    public void stopWork() {
+        System.out.println("Truck started its work");
+    }
+}