class RedBlackTree {

    public RedBlackNode<K,V> getFirst() {
        if (root == null) {
            return null;
        }
        RedBlackNode<K,V> node = root;

        while(node.left != null) {
            node = node.left;
        }
        return node;
    }

    public  RedBlackTree(Comparator<K> comparator, boolean allowDuplicateKeys);
    public  RedBlackTree(RedBlackTree<K, V> tree);

}