-er ddd dde ddr ddu ddx de- ded dee der deu dex drd dre drr dru drx dud due dur dux dxd dxr dxx ed- edd ede edr edu edx eed eee eer eex erd ere err eru eu- eud eue eur eux ex- exd exe exr exu exx rdd rde rdr rdu rdx re- red ree rer reu rex rrd rrr rru rud rue rur ruu rux rxr udd ude udr udu udx ued uee uer ur- urd ure urr uru urx uue uur uuu uxr uxu xde xdr xed xee xer xeu xex xrd xrx xue xxx