b-u bbb bbf bbk bbn bbo bbu bfb bff bfn bfo bfu bkb bkf bkk bkn bko bnb bnf bnk bnn bno bnu bob bof bok bon boo bou bub buf buk bun buo buu fbb fbf fbk fbn fbo fbu fff ffk ffn ffo ffu fkb fkf fkk fnb fnf fnk fnn fnu fob fof fok fon foo fou fub fuf fuk fun fuo fuu kbb kbf kbk kbn kbo kbu kff kfo kfu kkb kkk kkn kku kn- knf knk knn kno knu kob kof kok kon koo kou kub kuk kun kuu nbb nbf nbk nbn nbo nbu nfb nff nfk nfn nfo nfu nkf nkk nkn nko nku nnb nnf nnk nnn nno nnu no- nob nof nok non noo nou nub nuk nun nuo nuu ob- obb obf obk obn obo obu of- ofb off ofn ofo ofu okb okk oko oku on- onb onf onk onn ono onu oo- oob oof ook oon ooo ou- ouf ouk oun ouo ubb ubf ubk ubn ubo ubu uff ufn ufo ufu ukb ukf ukk ukn uku un- unb unf unk unn uno unu uob uok uon uoo uun uuu