hhh NNv NNbbb NN NNbbb NNbbb NN NN NNlll NNXXX NNXXX NN NN NN NNXXX NNbbb NN NNvvv NN&&& NN&&& NN NN NN::: NNXXX NNlll NNb|bb NN NN NN NN||||~ NNv|||v~v NN~ NNDD~D NN