bbb bbi bbk bbo bbs bi- bib bii bik bio bis bkb bkk bko bks bob boi bok boo bos bsb bsi bsk bso bss ibb ibi ibk ibo ibs iib iii iio iis ikb iki ikk iko iks io- iob ioi ioo ios is- isb isi isk iso iss kbb kbi kbk kbo kbs kib kii kik kio kis kkb kki kkk kks kob koi kok koo kos ksb ksi ksk kso kss o-i ob- obb obi obk obo obs oib oii oik oio ois okb oki okk oko oks oo- oob ooi ook ooo oos os- osb osi osk oso oss sbb sbi sbk sbo sbs sib sii sik sio sis sk- skb ski skk sko sks sob soi sok soo sos ss- ssb ssi ssk sso sss