import java.util.*;

class BinaryTree extends Tree {
   public BinaryTree() { super();}
   public Iterator children(Node v) {
      return v.children();
   }
   public void addRoot(Object x) {
      if (root != null) throw new RuntimeException();
      root = new BNode(x, null, null, null);
      size++;
   }
   public void addLeft(BNode n, Object x) {  
      if (n.getLeft() != null) throw new RuntimeException();
      n.setLeft(new BNode(x, n, null, null));
      size++;
   }
   public void addRight(BNode n, Object x) {  
      if (n.getRight() != null) throw new RuntimeException();
      n.setRight(new BNode(x, n, null, null));
      size++;
   }
   public Vector inOrder() {
      Vector answer = new Vector();
      inOrder((BNode) root(), answer);
      return answer;
   }
   public void inOrder(BNode n, Vector v) {
      if (n == null) return;
      inOrder(n.getLeft(), v);
      v.add(n);
      inOrder(n.getRight(), v);
   }
   public Vector flatOrder() {
      return inOrder();
   }
   public BNode leftmostRightDescendant(BNode n){
      if (n == null) return null;
      BNode m = n.getRight();
      if (m == null) return null;
      while (m.getLeft() != null) m = m.getLeft();
      return m;
   }
   public BNode rightmostLeftDescendant(BNode n){
      if (n == null) return null;
      BNode m = n.getLeft();
      if (m == null) return null;
      while (m.getRight() != null) m = m.getRight();
      return m;
   }
   public BNode removeNode(BNode n) {
      if (n.getLeft() != null) {
         BNode m = rightmostLeftDescendant(n);
         n.setData(m.getData());
         return removeNode(m);
      }
      if (n.getRight() != null) {
         BNode m = leftmostRightDescendant(n);
         n.setData(m.getData());
         return removeNode(m);
      }
      BNode p = (BNode) parent(n);
      if (p == null) {
         root = null;
      }
      else if (p.getLeft() == n) p.setLeft(null);
           else p.setRight(null);
      size --;
      return p;
   }
}

class BNode extends Node {
   BNode left, right;
   public BNode(Object d, BNode p, BNode l, BNode r) {
      super(d, p);
      left = l;
      right = r;
   }
   public void setLeft(BNode n) { left = n; }
   public void setRight(BNode n) { right = n; }
   public BNode getLeft() { return left; }
   public BNode getRight() { return right; }
   public Iterator children() {
      Vector v = new Vector();
      if (left != null) v.add(left);
      if (right != null) v.add(right);
      return v.iterator();
   }
}