bbb bbi bbk bbo bbr bbs bi- bib bii bik bio bir bis bkb bkk bko bkr bks bob boi bok boo bor bos brb bri brk bro brr brs bsb bsi bsk bso bsr bss ibb ibi ibk ibo ibr ibs iib iii iio iir iis ikb iki ikk iko ikr iks io- iob ioi ioo ior ios ir- irb iri irk iro irr irs is- isb isi isk iso isr iss kbb kbi kbk kbo kbr kbs kib kii kik kio kir kis kkb kki kkk kkr kks kob koi kok koo kor kos kri krk kro krr krs ksb ksi ksk kso ksr kss o-i ob- obb obi obk obo obr obs oib oii oik oio oir ois okb oki okk oko okr oks oo- oob ooi ook ooo oor oos or- orb ori ork oro orr ors os- osb osi osk oso osr oss rbb rbi rbk rbo rbr rbs rib rii rik rio rir ris rkb rkk rko rks rob roi rok roo ror ros rrb rri rrk rrr rrs rsb rsi rsk rso rsr rss sbb sbi sbk sbo sbr sbs sib sii sik sio sir sis sk- skb ski skk sko skr sks sob soi sok soo sor sos sr- srb sri srk sro srr srs ss- ssb ssi ssk sso ssr sss