interface BSTree {
   public void remove(Comparable x);
   public void insert(Comparable x);
   public boolean find(Comparable x);
}

class BST extends BinaryTree implements BSTree {
   public BNode findNode(Comparable x) {
      if (root() == null) return null;
      return findNode((BNode) root(), x);
   }
   public BNode findNode(BNode n, Comparable x) {
      BNode nn = null;
      if (((Comparable) n.getData()).compareTo(x) == 0) return n;
      if (((Comparable) n.getData()).compareTo(x) > 0) nn = n.getLeft();
      else nn = n.getRight();
      if (nn == null) return n;
      return findNode(nn, x);
   }
   public void remove(Comparable x) {
      BNode n = findNode(x);
      if (n == null || !n.getData().equals(x)) return;  // x is not present
      removeNode(n);
   }
   public void insert(Comparable x) {
      BNode n = findNode(x);
      if (n == null) addRoot(x);
      else if (((Comparable) n.getData()).compareTo(x) > 0) addLeft(n, x);
      else if (((Comparable) n.getData()).compareTo(x) < 0) addRight(n, x);
   }
   public boolean find(Comparable x) {
      BNode n = findNode(x);
      if (n == null || !n.getData().equals(x)) return false;
      return true;
   }
}