Task 1

src/Tree.java

@@ -1,2 +1,35 @@
+import java.util.ArrayList;
+
 public class Tree {
+    private Object root;
+    private  ArrayList<Tree> subtree;
+
+    public Tree( Object root, ArrayList<Tree> subtree){
+        this.root = root;
+        if (subtree == null){
+            this.subtree = new Arraylist<Tree>();
+        }
+        else {
+            this.subtree = subtree;
+        }
+    }
+
+    public boolean isEmpty(){
+        return this.root == null;
+    }
+
+    public int len(){
+        if (this.isEmpty()){
+            return 0;
+        }
+        else{
+            int size = 1;
+            for(Tree i : this.subtree){
+                size += i.len();
+            }
+            return size;
+        }
+    }
+
+
 }