class TreeSet<T extends Comparable<T>>{
    Node<T>{
        T item;
        Node<T> left = null;
        Node<T> right = null;

        Node(T i, Node<T> l, Node<T> r){
            item = i; left = l; right = r;
        }
    }

    private Node<T> root = null;
    private int numItems = 0;

    public int size(){
        return numItems;
    }

    public boolean isEmpty(){
        return root = null;
    }

    public boolean contains(T t){
        if(isEmpty())
            return false;
        Node<T> p = root;
        while(p != null && !p.item.equals(t)){
            if(t.compareTo(p.item) < 0)
                p = p.left;
            else
                p = p.right;
        }
        return p.item.equals(t);
    }

    public boolean add(T t){
        if(isEmpty()){
            root.item = t;
            numItems++;
            return true;
        }
        Node<T> p = root;
        while(p != null && !p.item.equals(t)){
            if(t.compareTo(p.item) < 0)
                p = p.left;
            else
                p = p.right;
        }
        if(!p.item.equals(t)){
            numItems++;
            p.item = p;
            return true;
        }
        else
            return false;
    }
}