-er -ic bbb bbc bbe bbi bbk bbr bcb bcc bce bci bck bcr be- beb bec bee bei bek ber bi- bib bic bie bii bik bir bkb bkc bke bkk bkr brb bre bri brk brr c-- cbb cbc cbe cbi cbk cbr ccb ccc cce cci cck ccr ce- ceb cec cee cei cek cer ci- cib cic cie cii cik cir ckb ckc cki crb crc cre cri crk crr ebb ebc ebe ebi ebk ebr ec- ecb ecc ece eci eck ecr eeb eec eee eek eer eib eic eie eii eik eir ekb ekc eke eki ekr erb erc ere eri erk err ibb ibc ibe ibi ibk ibr icb icc ice ici ick icr ie- iec iee iei iek ier iib iic iie iii iir ikb ikc ike iki ikk ikr ir- irb irc ire iri irk irr kbb kbc kbe kbi kbk kbr kcb kcc kce kci kck kcr ke- keb kec kee kei kek ker kib kic kie kii kik kir kkb kkc kke kki kkk kkr krc kri krk krr rbb rbc rbe rbi rbk rbr rcb rcc rce rci rcr re- reb rec ree rei rek rer rib ric rie rii rik rir rkb rkc rke rkk rrb rrc rri rrk rrr