-er bbb bbe bbi bbk bbo bbr bbs be- beb bee bei bek beo ber bes bez bi- bib bie bii bik bio bir bis biz bkb bke bkk bko bkr bks bob boe boi bok boo bor bos boz brb bre bri brk bro brr brs brz bsb bse bsi bsk bso bsr bss bze bzo bzr bzs bzz ebb ebe ebi ebk ebo ebr ebs eeb eee eek eeo eer ees eib eie eii eik eio eir eis ekb eke eki eko ekr eks eo- eob eoe eoi eok eoo eor eos erb ere eri erk ero err ers erz es- esb ese esi esk eso esr ess eze ezo ezr ezs ezz ibb ibe ibi ibk ibo ibr ibs ibz ie- iee iei iek ier ies iib iie iii iio iir iis ikb ike iki ikk iko ikr iks io- iob ioe ioi ioo ior ios ir- irb ire iri irk iro irr irs is- isb ise isi isk iso isr iss ize izi izo izz k-z kbb kbe kbi kbk kbo kbr kbs kbz ke- keb kee kei kek keo ker kes kez kib kie kii kik kio kir kis kiz kkb kke kki kkk kkr kks kob koe koi kok koo kor kos koz kri krk kro krr krs ksb kse ksi ksk kso ksr kss kzo o-i ob- obb obe obi obk obo obr obs oeb oee oei oeo oer oes oib oie oii oik oio oir ois oiz okb oke oki okk oko okr oks oo- oob ooi ook ooo oor oos or- orb ore ori ork oro orr ors orz os- osb ose osi osk oso osr oss oze ozo ozs ozz rbb rbe rbi rbk rbo rbr rbs re- reb ree rei rek reo rer res rez rib rie rii rik rio rir ris riz rkb rke rkk rko rks rkz rob roe roi rok roo ror ros roz rrb rri rrk rrr rrs rsb rse rsi rsk rso rsr rss rzb rze rzo sbb sbe sbi sbk sbo sbr sbs se- seb see sei sek seo ser ses sez sib sie sii sik sio sir sis sk- skb ske ski skk sko skr sks sob soe soi sok soo sor sos soz sr- srb sre sri srk sro srr srs ss- ssb sse ssi ssk sso ssr sss ssz sze szi szr zbb zbr zbs zeb zee zek zeo zer zes zez zib zie zik zio zir zis ziz zks zo- zob zoe zoi zok zoo zor zos zro zrs zse zsi zsz zzr zzs zzz