-er ddd dde ddo ddp ddr ddx de- ded dee deo dep der dex dod doe doo dop dor dox dpd dpe dpo dpp dpr drd dre dro drp drr drx dxd dxo dxp dxr dxx ed- edd ede edo edp edr edx eed eee eeo eep eer eex eo- eod eoe eoo eop eor ep- epd epe epo epp epr epx erd ere ero erp err ex- exd exe exo exp exr exx odd ode odo odp odr oed oee oeo oep oer oex oo- ood ooo oop oor oox op- opd ope opo opp opr opx or- ord ore oro orp orr orx ox- oxo oxx p-p pdd pde pdo pdp pdr pdx ped pee peo pep per pex pod poe poo pop por pox ppd ppe ppo ppp ppr ppx prd pre pro prp prr prx pxe pxr rdd rde rdo rdp rdr rdx re- red ree reo rep rer rex rod roe roo rop ror rox rpd rpe rpo rpp rpr rpx rrd rrp rrr rxp rxr xde xdr xed xee xep xer xex xod xoo xop xor xox xpd xpe xpo xpp xrd xrx xxo xxp xxx