-er c-- ccc cce ccf cco ccr ccs cct ce- cec cee cef ceo cer ces cet cfc cfe cff cfo cfr cfs cft co- coc coe cof coo cor cos cot crc cre crf cro crr crs crt csc cse csf cso csr css cst ctc cte ctf cto ctr cts ctt ec- ecc ece ecf eco ecr ecs ect eec eee eef eeo eer ees eet ef- efc efe eff efo efr efs eft eo- eoc eoe eof eoo eor eos eot erc ere erf ero err ers ert es- esc ese esf eso esr ess est etc ete etf eto etr ets ett fcc fce fcf fco fcr fcs fct fec fee fef feo fer fes fet ffc ffe fff ffo ffr ffs fft foc foe fof foo for fos fot frc fre frf fro frr frs frt fsc fse fsf fso fsr fss fst ftc fte ftf fto ftr fts ftt oc- occ ocf oco ocr ocs oct oec oee oef oeo oer oes oet of- ofc ofe off ofo ofr ofs oft oo- ooc oof ooo oor oos oot or- orc ore orf oro orr ors ort os- osc ose osf oso osr oss ost ot- otc ote otf oto otr ots ott rcc rce rcf rco rcr rcs rct re- rec ree ref reo rer res ret rfc rfe rff rfo rfr rfs rft roc roe rof roo ror ros rot rrc rrf rrr rrs rrt rsc rse rsf rso rsr rss rst rtc rte rtf rto rtr rts rtt scc sce scf sco scr scs sct se- sec see sef seo ser ses set sfc sfe sff sfo sfr sfs sft soc soe sof soo sor sos sot sr- src sre srf sro srr srs srt ss- ssc sse ssf sso ssr sss sst stc ste stf sto str sts stt tcc tce tcf tco tcr tcs tct te- tec tee tef teo ter tes tet tfc tfe tff tfo tfr tfs tft to- toc toe tof too tor tos tot trc tre trf tro trr trs trt tsc tse tsf tso tsr tss tst ttc tte ttf tto ttr tts ttt