-er a-a a-c a-t aaa aac aae aaf aar aas aat aax ac- aca acc ace acf acr acs act acx aea aec aee aef aer aes aet aex af- afa afc afe aff afr afs aft afx ar- ara arc are arf arr ars art arx as- asa asc ase asf asr ass ast asx at- ata atc ate atf atr ats att atx ax- axa axe axr axs axt axx c-- caa cac cae caf car cas cat cax cca ccc cce ccf ccr ccs cct ccx ce- cea cec cee cef cer ces cet cex cfa cfc cfe cff cfr cfs cft cfx cra crc cre crf crr crs crt crx csa csc cse csf csr css cst csx cta ctc cte ctf ctr cts ctt ctx cxc cxf cxr cxs cxt cxx eaa eac eae eaf ear eas eat eax ec- eca ecc ece ecf ecr ecs ect ecx eea eec eee eef eer ees eet eex ef- efa efc efe eff efr efs eft efx era erc ere erf err ers ert es- esa esc ese esf esr ess est esx eta etc ete etf etr ets ett etx ex- exa exc exe exr exs ext exx faa fac fae faf far fas fat fax fca fcc fce fcf fcr fcs fct fcx fea fec fee fef fer fes fet fex ffa ffc ffe fff ffr ffs fft ffx fra frc fre frf frr frs frt fsa fsc fse fsf fsr fss fst fsx fta ftc fte ftf ftr fts ftt ftx fxe fxr fxs fxt fxx ra- raa rac rae raf rar ras rat rax rca rcc rce rcf rcr rcs rct rcx re- rea rec ree ref rer res ret rex rfa rfc rfe rff rfr rfs rft rra rrc rrf rrr rrs rrt rsa rsc rse rsf rsr rss rst rsx rta rtc rte rtf rtr rts rtt rtx rxr rxs saa sac sae saf sar sas sat sax sca scc sce scf scr scs sct scx se- sea sec see sef ser ses set sex sfa sfc sfe sff sfr sfs sft sfx sr- sra src sre srf srr srs srt srx ss- ssa ssc sse ssf ssr sss sst ssx sta stc ste stf str sts stt stx sxc sxs sxt t-x taa tac tae taf tar tas tat tax tca tcc tce tcf tcr tcs tct tcx te- tea tec tee tef ter tes tet tex tfa tfc tfe tff tfr tfs tft tfx tra trc tre trf trr trs trt trx tsa tsc tse tsf tsr tss tst tsx tta ttc tte ttf ttr tts ttt ttx txe txf txs txt xaa xac xaf xar xas xat xcf xcr xcx xee xer xes xet xex xfa xfe xfs xft xfx xrc xrf xrt xrx xsa xsc xss xst xtc xtf xtr xts xtx xxx