-er -ic bbb bbc bbe bbi bbk bbo bbr bbt bcb bcc bce bci bck bco bcr bct be- beb bec bee bei bek beo ber bet bi- bib bic bie bii bik bio bir bit bkb bkc bke bkk bko bkr bkt bob boc boe boi bok boo bor bot brb bre bri brk bro brr brt btb btc bte bti btk bto btr btt c-- cbb cbc cbe cbi cbk cbo cbr cbt ccb ccc cce cci cck cco ccr cct ce- ceb cec cee cei cek ceo cer cet ci- cib cic cie cii cik cio cir cit ckb ckc cki cko ckt co- cob coc coe coi cok coo cor cot crb crc cre cri crk cro crr crt ctb ctc cte cti ctk cto ctr ctt ebb ebc ebe ebi ebk ebo ebr ebt ec- ecb ecc ece eci eck eco ecr ect eeb eec eee eek eeo eer eet eib eic eie eii eik eio eir eit ekb ekc eke eki eko ekr ekt eo- eob eoc eoe eoi eok eoo eor eot erb erc ere eri erk ero err ert etb etc ete eti etk eto etr ett ibb ibc ibe ibi ibk ibo ibr ibt icb icc ice ici ick ico icr ict ie- iec iee iei iek ier iet iib iic iie iii iio iir iit ikb ikc ike iki ikk iko ikr ikt io- iob ioc ioe ioi ioo ior iot ir- irb irc ire iri irk iro irr irt itb itc ite iti itk ito itt k-t kbb kbc kbe kbi kbk kbo kbr kcb kcc kce kci kck kcr kct ke- keb kec kee kei kek keo ker ket kib kic kie kii kik kio kir kit kkb kkc kke kki kkk kkr kkt kob koc koe koi kok koo kor kot krc kri krk kro krr krt ktb ktc kte ktk kto ktr ktt o-i ob- obb obc obe obi obk obo obr obt oc- ocb occ oci ock oco ocr oct oeb oec oee oei oeo oer oet oib oic oie oii oik oio oir oit okb okc oke oki okk oko okr oo- oob ooc ooi ook ooo oor oot or- orb orc ore ori ork oro orr ort ot- otb otc ote oti otk oto otr ott rbb rbc rbe rbi rbk rbo rbr rbt rcb rcc rce rci rco rcr rct re- reb rec ree rei rek reo rer ret rib ric rie rii rik rio rir rit rkb rkc rke rkk rko rkt rob roc roe roi rok roo ror rot rrb rrc rri rrk rrr rrt rtb rtc rte rti rtk rto rtr rtt tbb tbc tbe tbi tbk tbo tbr tbt tcb tcc tce tci tck tco tcr tct te- teb tec tee tei tek teo ter tet tib tic tie tii tik tio tir tit tkb tkc tke tkk tko tkr tkt to- tob toc toe toi tok too tor tot trb trc tre tri trk tro trr trt ttb ttc tte tti ttk tto ttr ttt