-er a-a a-c a-t aaa aac aae aaf aar aat aax ac- aca acc ace acf acr act acx aea aec aee aef aer aet aex af- afa afc afe aff afr aft afx ar- ara arc are arf arr art arx at- ata atc ate atf atr att atx ax- axa axe axr axt axx c-- caa cac cae caf car cat cax cca ccc cce ccf ccr cct ccx ce- cea cec cee cef cer cet cex cfa cfc cfe cff cfr cft cfx cra crc cre crf crr crt crx cta ctc cte ctf ctr ctt ctx cxc cxf cxr cxt cxx eaa eac eae eaf ear eat eax ec- eca ecc ece ecf ecr ect ecx eea eec eee eef eer eet eex ef- efa efc efe eff efr eft efx era erc ere erf err ert eta etc ete etf etr ett etx ex- exa exc exe exr ext exx faa fac fae faf far fat fax fca fcc fce fcf fcr fct fcx fea fec fee fef fer fet fex ffa ffc ffe fff ffr fft ffx fra frc fre frf frr frt fta ftc fte ftf ftr ftt ftx fxe fxr fxt fxx ra- raa rac rae raf rar rat rax rca rcc rce rcf rcr rct rcx re- rea rec ree ref rer ret rex rfa rfc rfe rff rfr rft rra rrc rrf rrr rrt rta rtc rte rtf rtr rtt rtx rxr t-x taa tac tae taf tar tat tax tca tcc tce tcf tcr tct tcx te- tea tec tee tef ter tet tex tfa tfc tfe tff tfr tft tfx tra trc tre trf trr trt trx tta ttc tte ttf ttr ttt ttx txe txf txt xaa xac xaf xar xat xcf xcr xcx xee xer xet xex xfa xfe xft xfx xrc xrf xrt xrx xtc xtf xtr xtx xxx