diff --git a/src/main/java/h06/problems/MazeSolverIterative.java b/src/main/java/h06/problems/MazeSolverIterative.java
index 9cf635e..c65d267 100644
--- a/src/main/java/h06/problems/MazeSolverIterative.java
+++ b/src/main/java/h06/problems/MazeSolverIterative.java
@@ -13,6 +13,7 @@
  *
  * @author Nhan Huynh
  */
+@DoNotTouch
 public class MazeSolverIterative implements MazeSolver {
 
     /**
diff --git a/src/main/java/h06/problems/MazeSolverRecursive.java b/src/main/java/h06/problems/MazeSolverRecursive.java
index ea072b5..b3eb420 100644
--- a/src/main/java/h06/problems/MazeSolverRecursive.java
+++ b/src/main/java/h06/problems/MazeSolverRecursive.java
@@ -13,6 +13,7 @@
  *
  * @author Nhan Huynh
  */
+@DoNotTouch
 public class MazeSolverRecursive implements MazeSolver {
 
     /**
diff --git a/src/main/java/h06/world/DirectionVector.java b/src/main/java/h06/world/DirectionVector.java
index 1699576..eaf949b 100644
--- a/src/main/java/h06/world/DirectionVector.java
+++ b/src/main/java/h06/world/DirectionVector.java
@@ -14,6 +14,7 @@
  *
  * @author Nhan Huynh
  */
+@DoNotTouch
 public enum DirectionVector {
 
     /**