-er ddd dde ddo ddr dds ddt ddx de- ded dee deo der des det dex dod doe doo dor dos dot dox drd dre dro drr drs drt drx dsd dse dso dsr dss dst dsx dtd dte dto dtr dts dtt dtx dxd dxo dxr dxs dxt dxx ed- edd ede edo edr eds edt edx eed eee eeo eer ees eet eex eo- eod eoe eoo eor eos eot erd ere ero err ers ert es- esd ese eso esr ess est esx etd ete eto etr ets ett etx ex- exd exe exo exr exs ext exx odd ode odo odr ods odt oed oee oeo oer oes oet oex oo- ood ooo oor oos oot oox or- ord ore oro orr ors ort orx os- osd ose oso osr oss ost osx ot- otd ote oto otr ots ott ox- oxo oxt oxx rdd rde rdo rdr rds rdt rdx re- red ree reo rer res ret rex rod roe roo ror ros rot rox rrd rrr rrs rrt rsd rse rso rsr rss rst rsx rtd rte rto rtr rts rtt rtx rxr rxs sdd sde sdo sdr sds sdt se- sed see seo ser ses set sex sod soe soo sor sos sot sox sr- srd sre sro srr srs srt srx ss- ssd sse sso ssr sss sst ssx std ste sto str sts stt stx sxs sxt t-x tdd tde tdo tdr tds tdt tdx te- ted tee teo ter tes tet tex to- tod toe too tor tos tot tox trd tre tro trr trs trt trx tsd tse tso tsr tss tst tsx ttd tte tto ttr tts ttt ttx txe txs txt xde xdr xds xdt xed xee xer xes xet xex xod xoo xor xos xot xox xrd xrt xrx xss xst xtr xts xtx xxo xxx