diff --git a/bin/app/App.class b/bin/app/App.class
index 02d8341..1e30390 100644
Binary files a/bin/app/App.class and b/bin/app/App.class differ
diff --git a/bin/app/BinaryNode.class b/bin/app/BinaryNode.class
new file mode 100644
index 0000000..ddd4fa0
Binary files /dev/null and b/bin/app/BinaryNode.class differ
diff --git a/bin/app/LinkedList.class b/bin/app/LinkedList.class
new file mode 100644
index 0000000..5d92d4d
Binary files /dev/null and b/bin/app/LinkedList.class differ
diff --git a/bin/app/Node.class b/bin/app/Node.class
new file mode 100644
index 0000000..ff48230
Binary files /dev/null and b/bin/app/Node.class differ
diff --git a/src/app/App.java b/src/app/App.java
index 49c5f22..7066605 100644
--- a/src/app/App.java
+++ b/src/app/App.java
@@ -3,20 +3,130 @@ package app;
 public class App {
     public static void main(String[] args) throws Exception {
         /** Aufgabe 1.1 - 1.3 */
-        System.out.println("++++ Aufgabe 1.1 - 1.3 ++++");
-        MyStack<String> stack = new MyStack<String>();
-        stack.push("hello");
-        stack.push("world");
-        stack.push("123");
-        System.out.println(stack.pop());
-        System.out.println(stack.pop());
-        System.out.println(stack.pop());
+        // System.out.println("++++ Aufgabe 1.1 - 1.3 ++++");
+        // MyStack<String> stack = new MyStack<String>();
+        // stack.push("hello");
+        // stack.push("world");
+        // stack.push("123");
+        // System.out.println(stack.pop());
+        // System.out.println(stack.pop());
+        // System.out.println(stack.pop());
 
-        /** Aufgabe 1.4 */
-        System.out.println("++++ Aufgabe 1.4 ++++");
-        tokenizeAndCalc("( 2 + 3 )");
-        tokenizeAndCalc("( 3 - ( 2 * 3 ) )");
-        tokenizeAndCalc("( ( 5 * 4 ) - ( 2 * ( 3 / 4 ) ) )");
+        // /** Aufgabe 1.4 */
+        // System.out.println("++++ Aufgabe 1.4 ++++");
+        // tokenizeAndCalc("( 2 + 3 )");
+        // tokenizeAndCalc("( 3 - ( 2 * 3 ) )");
+        // tokenizeAndCalc("( ( 5 * 4 ) - ( 2 * ( 3 / 4 ) ) )");
+
+        // /** Aufgabe 2.1 - 2.2 */
+        // System.out.println("++++ Aufgabe 2.1 - 2.2 ++++");
+        // Node<Integer> n1 = new Node<Integer>();
+        // Node<Integer> n2 = new Node<Integer>();
+        // Node<Integer> n3 = new Node<Integer>();
+        // Node<Integer> n4 = new Node<Integer>();
+        // n1.item = 1;
+        // n2.item = 2;
+        // n3.item = 3;
+        // n4.item = 4;
+        // n1.last = null;
+        // n1.next = n2;
+        // n2.last = n1;
+        // n2.next = n3;
+        // n3.last = n2;
+        // n3.next = n4;
+        // n4.last = n3;
+        // n4.next = null;
+        // n3.item = null;
+        // n2.next = n4;
+        // System.out.println(n1.item);
+        // System.out.println(n1.next.item);
+        // System.out.println(n1.next.next.item);
+
+        /** Aufgabe 3.1 */
+        System.out.println("++++ Aufgabe 3.1 ++++");
+        BinaryNode ba1 = new BinaryNode();
+        BinaryNode ba2 = new BinaryNode();
+        BinaryNode ba3 = new BinaryNode();
+        ba1.item = "+";
+        ba2.item = "2";
+        ba3.item = "3";
+        ba2.parent = ba1;
+        ba3.parent = ba1;
+        ba1.left = ba2;
+        ba1.right = ba2;
+
+        BinaryNode bb1 = new BinaryNode();
+        BinaryNode bb2 = new BinaryNode();
+        BinaryNode bb3 = new BinaryNode();
+        BinaryNode bb4 = new BinaryNode();
+        BinaryNode bb5 = new BinaryNode();
+        bb1.item = "*";
+        bb2.item = "5";
+        bb3.item = "+";
+        bb4.item = "2";
+        bb5.item = "3";
+        bb2.parent = bb1;
+        bb3.parent = bb1;
+        bb4.parent = bb3;
+        bb5.parent = bb3;
+        bb1.left = bb2;
+        bb1.right = bb3;
+        bb3.left = bb4;
+        bb3.left = bb5;
+
+        BinaryNode bc1 = new BinaryNode();
+        BinaryNode bc2 = new BinaryNode();
+        BinaryNode bc3 = new BinaryNode();
+        BinaryNode bc4 = new BinaryNode();
+        BinaryNode bc5 = new BinaryNode();
+        BinaryNode bc6 = new BinaryNode();
+        BinaryNode bc7 = new BinaryNode();
+        bc1.item = "+";
+        bc2.item = "*";
+        bc3.item = "2";
+        bc4.item = "3";
+        bc5.item = "*";
+        bc6.item = "4";
+        bc7.item = "5";
+        bc2.parent = bc1;
+        bc3.parent = bc2;
+        bc4.parent = bc2;
+        bc5.parent = bc1;
+        bc6.parent = bc5;
+        bc7.parent = bc5;
+        bc1.left = bc2;
+        bc1.right = bc5;
+        bc2.left = bc3;
+        bc2.right = bc4;
+        bc5.left = bc6;
+        bc5.right = bc7;
+
+        BinaryNode bd1 = new BinaryNode();
+        BinaryNode bd2 = new BinaryNode();
+        BinaryNode bd3 = new BinaryNode();
+        BinaryNode bd4 = new BinaryNode();
+        BinaryNode bd5 = new BinaryNode();
+        BinaryNode bd6 = new BinaryNode();
+        BinaryNode bd7 = new BinaryNode();
+        bd1.item = "*";
+        bd2.item = "2";
+        bd3.item = "+";
+        bd4.item = "3";
+        bd5.item = "4";
+        bd6.item = "*";
+        bd7.item = "5";
+        bd2.parent = bd1;
+        // bd3.parent = // Nicht möglich. Da Braum 3 Zweige benötigt.
+
+    }
+
+    private static boolean find(BinaryNode tree, String find) {
+        if (tree.item == find)
+            return true;
+        else {
+            // TODO: implement walk algorithm
+            return false || true;
+        }
     }
 
     private static void tokenizeAndCalc(String in) {
diff --git a/src/app/BinaryNode.java b/src/app/BinaryNode.java
new file mode 100644
index 0000000..2178b67
--- /dev/null
+++ b/src/app/BinaryNode.java
@@ -0,0 +1,8 @@
+package app;
+
+public class BinaryNode {
+    String item;
+    BinaryNode parent;
+    BinaryNode left;
+    BinaryNode right;
+}
\ No newline at end of file
diff --git a/src/app/LinkedList.java b/src/app/LinkedList.java
new file mode 100644
index 0000000..5ba7b3b
--- /dev/null
+++ b/src/app/LinkedList.java
@@ -0,0 +1,5 @@
+package app;
+
+public class LinkedList<Item> {
+    // TODO:
+}
\ No newline at end of file
diff --git a/src/app/Node.java b/src/app/Node.java
new file mode 100644
index 0000000..39202e1
--- /dev/null
+++ b/src/app/Node.java
@@ -0,0 +1,7 @@
+package app;
+
+public class Node<Item> {
+    Item item;
+    Node<Item> next;
+    Node<Item> last;
+}
\ No newline at end of file