a b a a b c d c c d e f e e f g h g g h b b i b b j i i j d d k d d l k k l f f m f f n m m n o q q p o o p s b d s s s f s s s q t s s 0 t s t t 0 0 0 o m k i 0 0 0 0 j 0 j 0 g e c a