bbbb bbrc bcbc bccc bcru bcuc brcb brkb brrr bruc bubb bubu bucc buck bucu bukk buku bur- burb burk burr buru cbbc cbcc cbcr cbcu cbkr ccbc cccb cccc cccu ccrc ccuc ckbc ckck ckrc crbc crbu crcc crcr crkc crub cruk cub- cubb cucc cuck cuk- curb curr kbbb kbbc kbbk kbbr kbbu kbcb kbck kbcr kbcu kbkb kbkk kbkr kbrb kbrc kbrk kbru kbub kbuc kbuk kbur kbuu kcbc kcbk kcbr kcbu kccb kccc kcck kccr kccu kckc kckk kckr kcrc kcrr kcru kcub kcuk kkbb kkbr kkcb kkck kkcr kkkk kkrb kkrc kkrk kkrr kkuu krbb krbk krbr krcb krcc krcu krkc krkk krkr krku krrb krrc krrk krrr kruc kruk krur kubb kubc kubr kubu kucb kucc kucr kukk kuku kurb kurk kurr kuru kuub kuuk kuur kuuu rbbb rbbr rcbc rccb rccc rrrr rubb rubu ruck rukk ruku rurc ruru ucbc ucrc ukcc ukrc ukur uruk urur uuuu