-er ddd dde ddf ddo ddr dds ddt ddx de- ded dee def deo der des det dex dfd dfe dff dfo dfr dfs dft dfx dod doe dof doo dor dos dot dox drd dre dro drr drs drt drx dsd dse dsf dso dsr dss dst dsx dtd dte dtf dto dtr dts dtt dtx dxd dxo dxr dxs dxt dxx ed- edd ede edf edo edr eds edt edx eed eee eef eeo eer ees eet eex ef- efd efe eff efo efr efs eft efx eo- eod eoe eof eoo eor eos eot erd ere erf ero err ers ert es- esd ese esf eso esr ess est esx etd ete etf eto etr ets ett etx ex- exd exe exo exr exs ext exx fdd fde fdf fdo fdr fds fdt fdx fed fee fef feo fer fes fet fex ffd ffe fff ffo ffr ffs fft ffx foe fof foo for fos fot fox frd fre frf fro frr frs frt fsd fse fsf fso fsr fss fst fsx ftd fte ftf fto ftr fts ftt ftx fxe fxr fxs fxt fxx odd ode odf odo odr ods odt oed oee oef oeo oer oes oet oex of- ofd ofe off ofo ofr ofs oft ofx oo- ood oof ooo oor oos oot oox or- ord ore orf oro orr ors ort orx os- osd ose osf oso osr oss ost osx ot- otd ote otf oto otr ots ott ox- oxf oxo oxt oxx rdd rde rdf rdo rdr rds rdt rdx re- red ree ref reo rer res ret rex rfd rfe rff rfo rfr rfs rft rod roe rof roo ror ros rot rox rrd rrf rrr rrs rrt rsd rse rsf rso rsr rss rst rsx rtd rte rtf rto rtr rts rtt rtx rxr rxs sdd sde sdf sdo sdr sds sdt se- sed see sef seo ser ses set sex sfd sfe sff sfo sfr sfs sft sfx sod soe sof soo sor sos sot sox sr- srd sre srf sro srr srs srt srx ss- ssd sse ssf sso ssr sss sst ssx std ste stf sto str sts stt stx sxs sxt t-x tdd tde tdf tdo tdr tds tdt tdx te- ted tee tef teo ter tes tet tex tfd tfe tff tfo tfr tfs tft tfx to- tod toe tof too tor tos tot tox trd tre trf tro trr trs trt trx tsd tse tsf tso tsr tss tst tsx ttd tte ttf tto ttr tts ttt ttx txe txf txs txt xde xdf xdr xds xdt xed xee xer xes xet xex xfe xfs xft xfx xod xof xoo xor xos xot xox xrd xrf xrt xrx xss xst xtf xtr xts xtx xxo xxx