bbb bbf bbi bbk bbo bbr bbs bfb bff bfi bfo bfr bfs bi- bib bif bii bik bio bir bis bkb bkf bkk bko bkr bks bob bof boi bok boo bor bos brb brf bri brk bro brr brs bsb bsf bsi bsk bso bsr bss fbb fbf fbi fbk fbo fbr fbs fff ffi ffk ffo ffr ffs fib fif fii fik fir fis fkb fkf fki fkk fob fof foi fok foo for fos frb frf fri frk fro frr frs fsb fsf fsi fsk fso fsr fss i-f ibb ibf ibi ibk ibo ibr ibs ifb iff ifi ifo ifr ifs iib iif iii iio iir iis ikb ikf iki ikk iko ikr iks io- iob iof ioi ioo ior ios ir- irb irf iri irk iro irr irs is- isb isf isi isk iso isr iss kbb kbf kbi kbk kbo kbr kbs kff kfi kfo kfs kib kif kii kik kio kir kis kkb kki kkk kkr kks kob kof koi kok koo kor kos krf kri krk kro krr krs ksb ksf ksi ksk kso ksr kss o-i ob- obb obf obi obk obo obr obs of- ofb off ofi ofo ofr ofs oib oif oii oik oio oir ois okb oki okk oko okr oks oo- oob oof ooi ook ooo oor oos or- orb orf ori ork oro orr ors os- osb osf osi osk oso osr oss rbb rbf rbi rbk rbo rbr rbs rfb rff rfi rfk rfo rfr rfs rib rif rii rik rio rir ris rkb rkf rkk rko rks rob rof roi rok roo ror ros rrb rrf rri rrk rrr rrs rsb rsf rsi rsk rso rsr rss sbb sbf sbi sbk sbo sbr sbs sfb sff sfi sfk sfo sfr sfs sib sif sii sik sio sir sis sk- skb skf ski skk sko skr sks sob sof soi sok soo sor sos sr- srb srf sri srk sro srr srs ss- ssb ssf ssi ssk sso ssr sss