b-u bbb bbk bbn bbo bbs bbu bkb bkk bkn bko bks bnb bnk bnn bno bns bnu bob bok bon boo bos bou bsb bsk bsn bso bss bsu bub buk bun buo bus buu kbb kbk kbn kbo kbs kbu kkb kkk kkn kks kku kn- knk knn kno knu kob kok kon koo kos kou ksb ksk ksn kso kss ksu kub kuk kun kus kuu nbb nbk nbn nbo nbs nbu nkk nkn nko nks nku nnb nnk nnn nno nns nnu no- nob nok non noo nos nou nsb nsk nsn nso nss nsu nub nuk nun nuo nus nuu ob- obb obk obn obo obs obu okb okk oko oks oku on- onb onk onn ono ons onu oo- oob ook oon ooo oos os- osb osk osn oso oss osu ou- ouk oun ouo ous sbb sbk sbn sbo sbs sbu sk- skb skk sko sks sku snb snk snn sno sns snu sob sok son soo sos sou ss- ssb ssk ssn sso sss ssu sub suk sun suo sus suu ubb ubk ubn ubo ubs ubu ukb ukk ukn uku un- unb unk unn uno uns unu uob uok uon uoo uos usb usk usn uso uss usu uun uus uuu