// 2-3 tree node implementation
class TTNode<Key extends Comparable<? super Key>,E> {
  private E lval;        // The left record
  private Key lkey;        // The node's left key
  private E rval;        // The right record
  private Key rkey;        // The node's right key
  private TTNode<Key,E> left;   // Pointer to left child
  private TTNode<Key,E> center; // Pointer to middle child
  private TTNode<Key,E> right;  // Pointer to right child

  public TTNode() { center = left = right = null; }
  public TTNode(Key lk, E lv, Key rk, E rv,
                TTNode<Key,E> p1, TTNode<Key,E> p2,
                TTNode<Key,E> p3) {
    lkey = lk; rkey = rk;
    lval = lv; rval = rv;
    left = p1; center = p2; right = p3;
  }

  public boolean isLeaf() { return left == null; }
  public TTNode<Key,E> lchild() { return left; }
  public TTNode<Key,E> rchild() { return right; }
  public TTNode<Key,E> cchild() { return center; }
  public Key lkey() { return lkey; }  // Left key
  public E lval() { return lval; }  // Left value
  public Key rkey() { return rkey; }  // Right key
  public E rval() { return rval; }  // Right value
  public void setLeft(Key k, E e) { lkey = k; lval = e; }
  public void setRight(Key k, E e) { rkey = k; rval = e; }
  public void setLeftChild(TTNode<Key,E> it) { left = it; }
  public void setCenterChild(TTNode<Key,E> it)
    { center = it; }
  public void setRightChild(TTNode<Key,E> it)
    { right = it; }
}