-er ddd dde ddp ddr dds ddx de- ded dee dep der des dex dpd dpe dpp dpr dps drd dre drp drr drs drx dsd dse dsp dsr dss dsx dxd dxp dxr dxs dxx ed- edd ede edp edr eds edx eed eee eep eer ees eex ep- epd epe epp epr eps epx erd ere erp err ers es- esd ese esp esr ess esx ex- exd exe exp exr exs exx p-p pdd pde pdp pdr pds pdx ped pee pep per pes pex ppd ppe ppp ppr pps ppx prd pre prp prr prs prx ps- psd pse psp psr pss psx pxe pxr pxs rdd rde rdp rdr rds rdx re- red ree rep rer res rex rpd rpe rpp rpr rps rpx rrd rrp rrr rrs rsd rse rsp rsr rss rsx rxp rxr rxs sdd sde sdp sdr sds se- sed see sep ser ses sex spd spe spp spr sps spx sr- srd sre srp srr srs srx ss- ssd sse ssp ssr sss ssx sxs xde xdr xds xed xee xep xer xes xex xpd xpe xpp xps xrd xrx xsp xss xxp xxx