-er ddd dde ddf ddo ddr de- ded dee def deo der dfd dfe dff dfo dfr dod doe dof doo dor drd dre dro drr ed- edd ede edf edo edr eed eee eef eeo eer ef- efd efe eff efo efr eo- eod eoe eof eoo eor erd ere erf ero err fdd fde fdf fdo fdr fed fee fef feo fer ffd ffe fff ffo ffr foe fof foo for frd fre frf fro frr odd ode odf odo odr oed oee oef oeo oer of- ofd ofe off ofo ofr oo- ood oof ooo oor or- ord ore orf oro orr rdd rde rdf rdo rdr re- red ree ref reo rer rfd rfe rff rfo rfr rod roe rof roo ror rrd rrf rrr