diff --git a/src/main/java/h06/Main.java b/src/main/java/h06/Main.java
index bcb69d7..cd09936 100644
--- a/src/main/java/h06/Main.java
+++ b/src/main/java/h06/Main.java
@@ -1,5 +1,14 @@
 package h06;
 
+import h06.problems.MazeSolverRecursive;
+import h06.problems.ProblemSolver;
+import h06.ui.MazeVisualizer;
+import h06.ui.ProblemVisualizer;
+import h06.world.DirectionVector;
+import h06.world.World;
+
+import java.awt.Point;
+
 /**
  * Main entry point in executing the program.
  */
@@ -12,5 +21,35 @@ public class Main {
      */
     public static void main(String[] args) {
         System.out.println("Hello World!");
+
+        World world = new World(5, 5);
+        Point start = new Point(2, 0);
+        Point end = new Point(2, 4);
+        DirectionVector direction = DirectionVector.UP;
+
+        world.placeWall(0, 0, false);
+        world.placeWall(0, 1, false);
+        world.placeWall(0, 2, false);
+        world.placeWall(0, 3, false);
+        world.placeWall(1, 3, false);
+        world.placeWall(1, 4, false);
+        world.placeWall(2, 0, false);
+        world.placeWall(3, 1, false);
+        world.placeWall(3, 3, false);
+
+        world.placeWall(1, 1, true);
+        world.placeWall(2, 0, true);
+        world.placeWall(2, 1, true);
+        world.placeWall(2, 2, true);
+        world.placeWall(3, 1, true);
+        world.placeWall(3, 3, true);
+        world.placeWall(4, 2, true);
+
+
+        ProblemVisualizer visualizer = new MazeVisualizer();
+        ProblemSolver solver = new MazeSolverRecursive();
+        visualizer.init(world);
+        visualizer.show();
+        visualizer.run(solver, start, end, direction);
     }
 }
diff --git a/src/main/java/h06/problems/MazeSolver.java b/src/main/java/h06/problems/MazeSolver.java
index a809de8..cd4692c 100644
--- a/src/main/java/h06/problems/MazeSolver.java
+++ b/src/main/java/h06/problems/MazeSolver.java
@@ -1,9 +1,12 @@
 package h06.problems;
 
+import org.tudalgo.algoutils.student.annotation.DoNotTouch;
+
 /**
  * A solver for a maze.
  *
  * @author Nhan Huynh
  */
+@DoNotTouch
 public interface MazeSolver extends ProblemSolver {
 }
diff --git a/src/main/java/h06/problems/MazeSolverIterative.java b/src/main/java/h06/problems/MazeSolverIterative.java
index 29f3c2a..9cf635e 100644
--- a/src/main/java/h06/problems/MazeSolverIterative.java
+++ b/src/main/java/h06/problems/MazeSolverIterative.java
@@ -2,6 +2,8 @@
 
 import h06.world.DirectionVector;
 import h06.world.World;
+import org.tudalgo.algoutils.student.annotation.DoNotTouch;
+import org.tudalgo.algoutils.student.annotation.StudentImplementationRequired;
 
 import java.awt.Point;
 
@@ -16,9 +18,11 @@ public class MazeSolverIterative implements MazeSolver {
     /**
      * Constructs an iterative maze solver.
      */
+    @DoNotTouch
     public MazeSolverIterative() {
     }
 
+    @StudentImplementationRequired
     @Override
     public DirectionVector nextStep(World world, Point p, DirectionVector d) {
         DirectionVector next = d.rotate270();
@@ -31,6 +35,7 @@ public DirectionVector nextStep(World world, Point p, DirectionVector d) {
         return d;
     }
 
+    @StudentImplementationRequired
     @Override
     public int numberOfSteps(World world, Point s, Point e, DirectionVector d) {
         int steps = 0;
@@ -45,6 +50,7 @@ public int numberOfSteps(World world, Point s, Point e, DirectionVector d) {
         return steps;
     }
 
+    @StudentImplementationRequired
     @Override
     public Point[] solve(World world, Point s, Point e, DirectionVector d) {
         int size = numberOfSteps(world, s, e, d);
diff --git a/src/main/java/h06/problems/MazeSolverRecursive.java b/src/main/java/h06/problems/MazeSolverRecursive.java
index 24c3772..ea072b5 100644
--- a/src/main/java/h06/problems/MazeSolverRecursive.java
+++ b/src/main/java/h06/problems/MazeSolverRecursive.java
@@ -2,6 +2,8 @@
 
 import h06.world.DirectionVector;
 import h06.world.World;
+import org.tudalgo.algoutils.student.annotation.DoNotTouch;
+import org.tudalgo.algoutils.student.annotation.StudentImplementationRequired;
 
 import java.awt.Point;
 
@@ -16,14 +18,17 @@ public class MazeSolverRecursive implements MazeSolver {
     /**
      * Constructs a recursive maze solver.
      */
+    @DoNotTouch
     public MazeSolverRecursive() {
     }
 
+    @StudentImplementationRequired
     @Override
     public DirectionVector nextStep(World world, Point p, DirectionVector d) {
         return !world.isBlocked(p, d.rotate270()) ? d.rotate270() : nextStep(world, p, d.rotate90());
     }
 
+    @StudentImplementationRequired
     @Override
     public int numberOfSteps(World world, Point s, Point e, DirectionVector d) {
         if (s.equals(e)) {
@@ -33,6 +38,7 @@ public int numberOfSteps(World world, Point s, Point e, DirectionVector d) {
         return 1 + numberOfSteps(world, next.getMovement(s), e, next);
     }
 
+    @StudentImplementationRequired
     @Override
     public Point[] solve(World world, Point s, Point e, DirectionVector d) {
         int size = numberOfSteps(world, s, e, d);
@@ -51,6 +57,7 @@ public Point[] solve(World world, Point s, Point e, DirectionVector d) {
      * @param path  the path calculated so far from s to p
      * @param index the index of the next free spot in path
      */
+    @StudentImplementationRequired
     private void solveHelper(World world, Point p, Point e, DirectionVector d, Point[] path, int index) {
         if (p.equals(e)) {
             path[index] = p;
diff --git a/src/main/java/h06/problems/ProblemSolver.java b/src/main/java/h06/problems/ProblemSolver.java
index 4d6b3ca..c8643e1 100644
--- a/src/main/java/h06/problems/ProblemSolver.java
+++ b/src/main/java/h06/problems/ProblemSolver.java
@@ -2,6 +2,7 @@
 
 import h06.world.DirectionVector;
 import h06.world.World;
+import org.tudalgo.algoutils.student.annotation.DoNotTouch;
 
 import java.awt.Point;
 
@@ -10,6 +11,7 @@
  *
  * @author Nhan Huynh
  */
+@DoNotTouch
 public interface ProblemSolver {
 
     /**
diff --git a/src/main/java/h06/ui/MazeVisualizer.java b/src/main/java/h06/ui/MazeVisualizer.java
index 7807f57..babb4db 100644
--- a/src/main/java/h06/ui/MazeVisualizer.java
+++ b/src/main/java/h06/ui/MazeVisualizer.java
@@ -5,6 +5,7 @@
 import h06.problems.ProblemSolver;
 import h06.world.DirectionVector;
 import h06.world.World;
+import org.tudalgo.algoutils.student.annotation.DoNotTouch;
 
 import java.awt.Color;
 import java.awt.Point;
@@ -14,6 +15,7 @@
  *
  * @author Nhan Huynh
  */
+@DoNotTouch
 public class MazeVisualizer implements ProblemVisualizer {
 
     /**
diff --git a/src/main/java/h06/ui/ProblemVisualizer.java b/src/main/java/h06/ui/ProblemVisualizer.java
index 710d122..3c17cb7 100644
--- a/src/main/java/h06/ui/ProblemVisualizer.java
+++ b/src/main/java/h06/ui/ProblemVisualizer.java
@@ -3,6 +3,7 @@
 import h06.problems.ProblemSolver;
 import h06.world.DirectionVector;
 import h06.world.World;
+import org.tudalgo.algoutils.student.annotation.DoNotTouch;
 
 import java.awt.Point;
 
@@ -11,6 +12,7 @@
  *
  * @author Nhan Huynh
  */
+@DoNotTouch
 public interface ProblemVisualizer {
 
     /**
diff --git a/src/main/java/h06/world/DirectionVector.java b/src/main/java/h06/world/DirectionVector.java
index 3383b5a..814423e 100644
--- a/src/main/java/h06/world/DirectionVector.java
+++ b/src/main/java/h06/world/DirectionVector.java
@@ -1,5 +1,7 @@
 package h06.world;
 
+import org.tudalgo.algoutils.student.annotation.StudentImplementationRequired;
+
 import java.awt.Point;
 
 /**
@@ -59,6 +61,7 @@ public enum DirectionVector {
      *
      * @return the direction vector counterclockwise to this direction vector
      */
+    @StudentImplementationRequired
     public DirectionVector rotate270() {
         return this == UP ? LEFT : this == LEFT ? DOWN : this == DOWN ? RIGHT : UP;
     }
@@ -68,6 +71,7 @@ public DirectionVector rotate270() {
      *
      * @return the direction vector clockwise to this direction vector
      */
+    @StudentImplementationRequired
     public DirectionVector rotate90() {
         if (this == UP) {
             return RIGHT;
diff --git a/src/main/java/h06/world/Field.java b/src/main/java/h06/world/Field.java
index e41c3cc..8fa74b2 100644
--- a/src/main/java/h06/world/Field.java
+++ b/src/main/java/h06/world/Field.java
@@ -1,12 +1,14 @@
 package h06.world;
 
 import fopbot.FieldEntity;
+import org.tudalgo.algoutils.student.annotation.DoNotTouch;
 
 /**
  * A field in a world which can contains entities.
  *
  * @author Nhan Huynh
  */
+@DoNotTouch
 public class Field {
 
     /**
diff --git a/src/main/java/h06/world/Wall.java b/src/main/java/h06/world/Wall.java
index 9b538db..b990b28 100644
--- a/src/main/java/h06/world/Wall.java
+++ b/src/main/java/h06/world/Wall.java
@@ -1,12 +1,14 @@
 package h06.world;
 
 import fopbot.FieldEntity;
+import org.tudalgo.algoutils.student.annotation.DoNotTouch;
 
 /**
  * A wall with orientation.
  *
  * @author Nhan Huynh
  */
+@DoNotTouch
 public class Wall extends FieldEntity {
 
     /**
diff --git a/src/main/java/h06/world/World.java b/src/main/java/h06/world/World.java
index 49da027..05aa32e 100644
--- a/src/main/java/h06/world/World.java
+++ b/src/main/java/h06/world/World.java
@@ -2,6 +2,7 @@
 
 import fopbot.Field;
 import fopbot.FieldEntity;
+import org.tudalgo.algoutils.student.annotation.StudentImplementationRequired;
 
 import java.awt.Point;
 
@@ -126,6 +127,7 @@ public boolean isBlocked(int x, int y, boolean horizontal) {
      * @param d the direction vector to add to the point
      * @return {@code true} if the position is blocked, {@code false} otherwise
      */
+    @StudentImplementationRequired
     public boolean isBlocked(Point p, DirectionVector d) {
         // Outside
         if (isOutside(p, d)) {