-er -ic bbb bbc bbe bbi bbk bbo bbr bcb bcc bce bci bck bco bcr be- beb bec bee bei bek beo ber bi- bib bic bie bii bik bio bir bkb bkc bke bkk bko bkr bob boc boe boi bok boo bor brb bre bri brk bro brr c-- cbb cbc cbe cbi cbk cbo cbr ccb ccc cce cci cck cco ccr ce- ceb cec cee cei cek ceo cer ci- cib cic cie cii cik cio cir ckb ckc cki cko co- cob coc coe coi cok coo cor crb crc cre cri crk cro crr ebb ebc ebe ebi ebk ebo ebr ec- ecb ecc ece eci eck eco ecr eeb eec eee eek eeo eer eib eic eie eii eik eio eir ekb ekc eke eki eko ekr eo- eob eoc eoe eoi eok eoo eor erb erc ere eri erk ero err ibb ibc ibe ibi ibk ibo ibr icb icc ice ici ick ico icr ie- iec iee iei iek ier iib iic iie iii iio iir ikb ikc ike iki ikk iko ikr io- iob ioc ioe ioi ioo ior ir- irb irc ire iri irk iro irr kbb kbc kbe kbi kbk kbo kbr kcb kcc kce kci kck kcr ke- keb kec kee kei kek keo ker kib kic kie kii kik kio kir kkb kkc kke kki kkk kkr kob koc koe koi kok koo kor krc kri krk kro krr o-i ob- obb obc obe obi obk obo obr oc- ocb occ oci ock oco ocr oeb oec oee oei oeo oer oib oic oie oii oik oio oir okb okc oke oki okk oko okr oo- oob ooc ooi ook ooo oor or- orb orc ore ori ork oro orr rbb rbc rbe rbi rbk rbo rbr rcb rcc rce rci rco rcr re- reb rec ree rei rek reo rer rib ric rie rii rik rio rir rkb rkc rke rkk rko rob roc roe roi rok roo ror rrb rrc rri rrk rrr