-er ddd dde ddn ddo ddr ddx de- ded dee den deo der dex dnd dne dnn dno dnr dod doe don doo dor dox drd dre drn dro drr drx dxd dxn dxo dxr dxx ed- edd ede edn edo edr edx eed eee een eeo eer eex en- end ene enn eno enr eo- eod eoe eon eoo eor erd ere ern ero err ex- exd exe exo exr exx ndd nde ndn ndo ndr ne- ned nee nen neo ner nex nne nnn nno no- nod noe non noo nor nox nrd nre nrn nro nrr nrx nxd odd ode odn odo odr oed oee oen oeo oer oex on- ond one onn ono onr onx oo- ood oon ooo oor oox or- ord ore orn oro orr orx ox- oxn oxo oxx rdd rde rdn rdo rdr rdx re- red ree ren reo rer rex rnd rnn rno rnr rod roe ron roo ror rox rrd rrn rrr rxr xde xdr xed xee xen xer xex xno xod xon xoo xor xox xrd xrx xxo xxx