-er ddd dde ddf ddo ddr ddt ddx de- ded dee def deo der det dex dfd dfe dff dfo dfr dft dfx dod doe dof doo dor dot dox drd dre dro drr drt drx dtd dte dtf dto dtr dtt dtx dxd dxo dxr dxt dxx ed- edd ede edf edo edr edt edx eed eee eef eeo eer eet eex ef- efd efe eff efo efr eft efx eo- eod eoe eof eoo eor eot erd ere erf ero err ert etd ete etf eto etr ett etx ex- exd exe exo exr ext exx fdd fde fdf fdo fdr fdt fdx fed fee fef feo fer fet fex ffd ffe fff ffo ffr fft ffx foe fof foo for fot fox frd fre frf fro frr frt ftd fte ftf fto ftr ftt ftx fxe fxr fxt fxx odd ode odf odo odr odt oed oee oef oeo oer oet oex of- ofd ofe off ofo ofr oft ofx oo- ood oof ooo oor oot oox or- ord ore orf oro orr ort orx ot- otd ote otf oto otr ott ox- oxf oxo oxt oxx rdd rde rdf rdo rdr rdt rdx re- red ree ref reo rer ret rex rfd rfe rff rfo rfr rft rod roe rof roo ror rot rox rrd rrf rrr rrt rtd rte rtf rto rtr rtt rtx rxr t-x tdd tde tdf tdo tdr tdt tdx te- ted tee tef teo ter tet tex tfd tfe tff tfo tfr tft tfx to- tod toe tof too tor tot tox trd tre trf tro trr trt trx ttd tte ttf tto ttr ttt ttx txe txf txt xde xdf xdr xdt xed xee xer xet xex xfe xft xfx xod xof xoo xor xot xox xrd xrf xrt xrx xtf xtr xtx xxo xxx