-er ddd dde ddo ddp ddr de- ded dee deo dep der dod doe doo dop dor dpd dpe dpo dpp dpr drd dre dro drp drr ed- edd ede edo edp edr eed eee eeo eep eer eo- eod eoe eoo eop eor ep- epd epe epo epp epr erd ere ero erp err odd ode odo odp odr oed oee oeo oep oer oo- ood ooo oop oor op- opd ope opo opp opr or- ord ore oro orp orr p-p pdd pde pdo pdp pdr ped pee peo pep per pod poe poo pop por ppd ppe ppo ppp ppr prd pre pro prp prr rdd rde rdo rdp rdr re- red ree reo rep rer rod roe roo rop ror rpd rpe rpo rpp rpr rrd rrp rrr