-er c-- ccc cce ccf ccr ccs cct ce- cec cee cef cer ces cet cfc cfe cff cfr cfs cft crc cre crf crr crs crt csc cse csf csr css cst ctc cte ctf ctr cts ctt ec- ecc ece ecf ecr ecs ect eec eee eef eer ees eet ef- efc efe eff efr efs eft erc ere erf err ers ert es- esc ese esf esr ess est etc ete etf etr ets ett fcc fce fcf fcr fcs fct fec fee fef fer fes fet ffc ffe fff ffr ffs fft frc fre frf frr frs frt fsc fse fsf fsr fss fst ftc fte ftf ftr fts ftt rcc rce rcf rcr rcs rct re- rec ree ref rer res ret rfc rfe rff rfr rfs rft rrc rrf rrr rrs rrt rsc rse rsf rsr rss rst rtc rte rtf rtr rts rtt scc sce scf scr scs sct se- sec see sef ser ses set sfc sfe sff sfr sfs sft sr- src sre srf srr srs srt ss- ssc sse ssf ssr sss sst stc ste stf str sts stt tcc tce tcf tcr tcs tct te- tec tee tef ter tes tet tfc tfe tff tfr tfs tft trc tre trf trr trs trt tsc tse tsf tsr tss tst ttc tte ttf ttr tts ttt