-er eee eef eel eer ees eet eex ef- efe eff efl efr efs eft efx ele elf ell elr els elt elx ere erf erl err ers ert es- ese esf esl esr ess est esx ete etf etl etr ets ett etx ex- exe exl exr exs ext exx fee fef fel fer fes fet fex ffe fff ffl ffr ffs fft ffx fle flf fll flr fls flt flx fre frf frl frr frs frt fse fsf fsl fsr fss fst fsx fte ftf ftl ftr fts ftt ftx fxe fxr fxs fxt fxx lee lef lel ler les let lex lfe lff lfl lfr lfs lft lfx lle llf lll llr lls llt lrf lrr lrs lrt lse lsf lsl lsr lss lst lte ltf ltl ltr lts ltt ltx lxr lxx re- ree ref rel rer res ret rex rfe rff rfl rfr rfs rft rle rlf rll rlr rls rlt rrf rrl rrr rrs rrt rse rsf rsl rsr rss rst rsx rte rtf rtl rtr rts rtt rtx rxr rxs se- see sef sel ser ses set sex sfe sff sfl sfr sfs sft sfx sle slf sll slr sls slt slx sr- sre srf srl srr srs srt srx ss- sse ssf ssl ssr sss sst ssx ste stf stl str sts stt stx sxl sxs sxt t-x te- tee tef tel ter tes tet tex tfe tff tfl tfr tfs tft tfx tle tlf tll tlr tls tlt tlx tre trf trl trr trs trt trx tse tsf tsl tsr tss tst tsx tte ttf ttl ttr tts ttt ttx txe txf txl txs txt xee xel xer xes xet xex xfe xfl xfs xft xfx xlf xlr xls xlt xrf xrt xrx xsl xss xst xtf xtr xts xtx xxl xxx