b-u bbb bbc bbk bbn bbo bbr bbu bcb bcc bck bcn bco bcr bcu bkb bkc bkk bkn bko bkr bnb bnc bnk bnn bno bnr bnu bob boc bok bon boo bor bou brb brk brn bro brr bru bub buc buk bun buo bur buu c-- cbb cbc cbk cbn cbo cbr cbu ccb ccc cck ccn cco ccr ccu ckb ckc cko cn- cnb cnc cnn cno cnr cnu co- cob coc cok con coo cor cou crb crc crk crn cro crr cru cub cuc cuk cun cuo cur cuu kbb kbc kbk kbn kbo kbr kbu kcb kcc kck kcn kcr kcu kkb kkc kkk kkn kkr kku kn- knc knk knn kno knr knu kob koc kok kon koo kor kou krc krk krn kro krr kru kub kuc kuk kun kur kuu nbb nbc nbk nbn nbo nbr nbu ncb ncc nck ncn nco ncr ncu nkc nkk nkn nko nkr nku nnb nnc nnk nnn nno nnu no- nob noc nok non noo nor nou nrb nrc nrk nrn nro nrr nru nub nuc nuk nun nuo nur nuu ob- obb obc obk obn obo obr obu oc- ocb occ ock ocn oco ocr ocu okb okc okk oko okr oku on- onb onc onk onn ono onr onu oo- oob ooc ook oon ooo oor or- orb orc ork orn oro orr oru ou- ouc ouk oun ouo our rbb rbc rbk rbn rbo rbr rbu rcb rcc rcn rco rcr rcu rkb rkc rkk rko rku rnb rnc rnn rno rnr rnu rob roc rok ron roo ror rou rrb rrc rrk rrn rrr rru rub ruc ruk run ruo rur ruu ubb ubc ubk ubn ubo ubr ubu ucb ucc uck ucn uco ucr ucu ukb ukc ukk ukn ukr uku un- unb unc unk unn uno unr unu uob uoc uok uon uoo uor ur- urb urc urk urn uro urr uru uuc uun uur uuu