-er ddd dde ddo ddr dds ddx de- ded dee deo der des dex dod doe doo dor dos dox drd dre dro drr drs drx dsd dse dso dsr dss dsx dxd dxo dxr dxs dxx ed- edd ede edo edr eds edx eed eee eeo eer ees eex eo- eod eoe eoo eor eos erd ere ero err ers es- esd ese eso esr ess esx ex- exd exe exo exr exs exx odd ode odo odr ods oed oee oeo oer oes oex oo- ood ooo oor oos oox or- ord ore oro orr ors orx os- osd ose oso osr oss osx ox- oxo oxx rdd rde rdo rdr rds rdx re- red ree reo rer res rex rod roe roo ror ros rox rrd rrr rrs rsd rse rso rsr rss rsx rxr rxs sdd sde sdo sdr sds se- sed see seo ser ses sex sod soe soo sor sos sox sr- srd sre sro srr srs srx ss- ssd sse sso ssr sss ssx sxs xde xdr xds xed xee xer xes xex xod xoo xor xos xox xrd xrx xss xxo xxx