-er ddd dde ddo ddr ddt ddx de- ded dee deo der det dex dod doe doo dor dot dox drd dre dro drr drt drx dtd dte dto dtr dtt dtx dxd dxo dxr dxt dxx ed- edd ede edo edr edt edx eed eee eeo eer eet eex eo- eod eoe eoo eor eot erd ere ero err ert etd ete eto etr ett etx ex- exd exe exo exr ext exx odd ode odo odr odt oed oee oeo oer oet oex oo- ood ooo oor oot oox or- ord ore oro orr ort orx ot- otd ote oto otr ott ox- oxo oxt oxx rdd rde rdo rdr rdt rdx re- red ree reo rer ret rex rod roe roo ror rot rox rrd rrr rrt rtd rte rto rtr rtt rtx rxr t-x tdd tde tdo tdr tdt tdx te- ted tee teo ter tet tex to- tod toe too tor tot tox trd tre tro trr trt trx ttd tte tto ttr ttt ttx txe txt xde xdr xdt xed xee xer xet xex xod xoo xor xot xox xrd xrt xrx xtr xtx xxo xxx