-er ddd dde ddi ddp ddr dds ddt ddx de- ded dee dei dep der des det dex di- did die dii dip dir dis dit dix dpd dpe dpi dpp dpr dps dpt drd dre dri drp drr drs drt drx dsd dse dsi dsp dsr dss dst dsx dtd dte dti dtp dtr dts dtt dtx dxd dxi dxp dxr dxs dxt dxx ed- edd ede edi edp edr eds edt edx eed eee eep eer ees eet eex eid eie eii eip eir eis eit eix ep- epd epe epi epp epr eps ept epx erd ere eri erp err ers ert es- esd ese esi esp esr ess est esx etd ete eti etp etr ets ett etx ex- exd exe exi exp exr exs ext exx i-d idd ide idi idp idr ids idt idx ie- ied iee iei iep ier ies iet iex iid iie iii iip iir iis iit iix ipd ipe ipi ipp ipr ips ipt ipx ir- ird ire iri irp irr irs irt irx is- isd ise isi isp isr iss ist itd ite iti itp its itt itx ixe ixi p-p pdd pde pdi pdp pdr pds pdt pdx ped pee pei pep per pes pet pex pid pie pii pip pir pis pit pix ppd ppe ppi ppp ppr pps ppt ppx prd pre pri prp prr prs prt prx ps- psd pse psi psp psr pss pst psx pt- ptd pte pti ptp ptr pts ptt ptx pxe pxr pxs pxt rdd rde rdi rdp rdr rds rdt rdx re- red ree rei rep rer res ret rex rid rie rii rip rir ris rit rix rpd rpe rpi rpp rpr rps rpt rpx rrd rri rrp rrr rrs rrt rsd rse rsi rsp rsr rss rst rsx rtd rte rti rtp rtr rts rtt rtx rxp rxr rxs sdd sde sdi sdp sdr sds sdt se- sed see sei sep ser ses set sex sid sie sii sip sir sis sit six spd spe spi spp spr sps spt spx sr- srd sre sri srp srr srs srt srx ss- ssd sse ssi ssp ssr sss sst ssx std ste sti stp str sts stt stx sxi sxs sxt t-x tdd tde tdi tdp tdr tds tdt tdx te- ted tee tei tep ter tes tet tex tid tie tii tip tir tis tit tix tpd tpe tpi tpp tpr tps tpt tpx trd tre tri trp trr trs trt trx tsd tse tsi tsp tsr tss tst tsx ttd tte tti ttp ttr tts ttt ttx txe txi txs txt xde xdi xdr xds xdt xed xee xep xer xes xet xex xie xii xis xit xix xpd xpe xpp xps xpt xrd xrt xrx xsi xsp xss xst xti xtp xtr xts xtx xxi xxp xxx