-er ddd dde ddi ddr dds ddt ddx de- ded dee dei der des det dex di- did die dii dir dis dit dix drd dre dri drr drs drt drx dsd dse dsi dsr dss dst dsx dtd dte dti dtr dts dtt dtx dxd dxi dxr dxs dxt dxx ed- edd ede edi edr eds edt edx eed eee eer ees eet eex eid eie eii eir eis eit eix erd ere eri err ers ert es- esd ese esi esr ess est esx etd ete eti etr ets ett etx ex- exd exe exi exr exs ext exx i-d idd ide idi idr ids idt idx ie- ied iee iei ier ies iet iex iid iie iii iir iis iit iix ir- ird ire iri irr irs irt irx is- isd ise isi isr iss ist itd ite iti its itt itx ixe ixi rdd rde rdi rdr rds rdt rdx re- red ree rei rer res ret rex rid rie rii rir ris rit rix rrd rri rrr rrs rrt rsd rse rsi rsr rss rst rsx rtd rte rti rtr rts rtt rtx rxr rxs sdd sde sdi sdr sds sdt se- sed see sei ser ses set sex sid sie sii sir sis sit six sr- srd sre sri srr srs srt srx ss- ssd sse ssi ssr sss sst ssx std ste sti str sts stt stx sxi sxs sxt t-x tdd tde tdi tdr tds tdt tdx te- ted tee tei ter tes tet tex tid tie tii tir tis tit tix trd tre tri trr trs trt trx tsd tse tsi tsr tss tst tsx ttd tte tti ttr tts ttt ttx txe txi txs txt xde xdi xdr xds xdt xed xee xer xes xet xex xie xii xis xit xix xrd xrt xrx xsi xss xst xti xtr xts xtx xxi xxx