bbbb bbrc bcbc bccc bnrr brcb brkb brrr cbbc cbcc cbcn cbcr cbkn cbkr cbrn ccbc ccbn cccb cccc ccnb ccnc ccnr ccrc ckbc ckck cknb cknc ckrc cnbc cnrc cnrr crbc crcc crcr crkc kbbb kbbc kbbk kbbr kbcb kbck kbcr kbkb kbkk kbkr kbnn kbnr kbrb kbrc kbrk kbrn kcbc kcbk kcbr kccb kccc kcck kccr kckc kckk kckn kckr kcnb kcnr kcrc kcrn kcrr kkbb kkbn kkbr kkcb kkck kkcn kkcr kkkk kknb kknn kkrb kkrc kkrk kkrn kkrr knbb knbc knbn knbr kncb knck kncn kncr knkk knnb knnk knnr knrb knrk krbb krbk krbr krcb krcc krcn krkc krkk krkn krkr krnb krnk krnn krrb krrc krrk krrn krrr nbbc nbcc ncbc nccc nccn nccr ncnc ncrc nnnn nrrc rbbb rbbr rcbc rccb rccc rcnr rnbr rrrr