-er -ic bbb bbc bbe bbi bbk bbo bbr bbs bcb bcc bce bci bck bco bcr bcs be- beb bec bee bei bek beo ber bes bi- bib bic bie bii bik bio bir bis bkb bkc bke bkk bko bkr bks bob boc boe boi bok boo bor bos brb bre bri brk bro brr brs bsb bsc bse bsi bsk bso bsr bss c-- cbb cbc cbe cbi cbk cbo cbr cbs ccb ccc cce cci cck cco ccr ccs ce- ceb cec cee cei cek ceo cer ces ci- cib cic cie cii cik cio cir cis ckb ckc cki cko cks co- cob coc coe coi cok coo cor cos crb crc cre cri crk cro crr crs csb csc cse csi csk cso csr css ebb ebc ebe ebi ebk ebo ebr ebs ec- ecb ecc ece eci eck eco ecr ecs eeb eec eee eek eeo eer ees eib eic eie eii eik eio eir eis ekb ekc eke eki eko ekr eks eo- eob eoc eoe eoi eok eoo eor eos erb erc ere eri erk ero err ers es- esb esc ese esi esk eso esr ess ibb ibc ibe ibi ibk ibo ibr ibs icb icc ice ici ick ico icr ics ie- iec iee iei iek ier ies iib iic iie iii iio iir iis ikb ikc ike iki ikk iko ikr iks io- iob ioc ioe ioi ioo ior ios ir- irb irc ire iri irk iro irr irs is- isb isc ise isi isk iso isr iss kbb kbc kbe kbi kbk kbo kbr kbs kcb kcc kce kci kck kcr kcs ke- keb kec kee kei kek keo ker kes kib kic kie kii kik kio kir kis kkb kkc kke kki kkk kkr kks kob koc koe koi kok koo kor kos krc kri krk kro krr krs ksb ksc kse ksi ksk kso ksr kss o-i ob- obb obc obe obi obk obo obr obs oc- ocb occ oci ock oco ocr ocs oeb oec oee oei oeo oer oes oib oic oie oii oik oio oir ois okb okc oke oki okk oko okr oks oo- oob ooc ooi ook ooo oor oos or- orb orc ore ori ork oro orr ors os- osb osc ose osi osk oso osr oss rbb rbc rbe rbi rbk rbo rbr rbs rcb rcc rce rci rco rcr rcs re- reb rec ree rei rek reo rer res rib ric rie rii rik rio rir ris rkb rkc rke rkk rko rks rob roc roe roi rok roo ror ros rrb rrc rri rrk rrr rrs rsb rsc rse rsi rsk rso rsr rss sbb sbc sbe sbi sbk sbo sbr sbs scb scc sce sci sck sco scr scs se- seb sec see sei sek seo ser ses sib sic sie sii sik sio sir sis sk- skb skc ske ski skk sko skr sks sob soc soe soi sok soo sor sos sr- srb src sre sri srk sro srr srs ss- ssb ssc sse ssi ssk sso ssr sss