-er ddd dde ddn ddr ddt ddx de- ded dee den der det dex dnd dne dnn dnr dnt drd dre drn drr drt drx dtd dte dtn dtr dtt dtx dxd dxn dxr dxt dxx ed- edd ede edn edr edt edx eed eee een eer eet eex en- end ene enn enr ent erd ere ern err ert etd ete etn etr ett etx ex- exd exe exr ext exx ndd nde ndn ndr ndt ne- ned nee nen ner net nex nne nnn nnt nrd nre nrn nrr nrt nrx ntd nte ntn ntr ntt ntx nxd nxt rdd rde rdn rdr rdt rdx re- red ree ren rer ret rex rnd rnn rnr rnt rrd rrn rrr rrt rtd rte rtn rtr rtt rtx rxr t-x tdd tde tdn tdr tdt tdx te- ted tee ten ter tet tex tnd tne tnn tnr tnt tnx trd tre trn trr trt trx ttd tte ttn ttr ttt ttx txe txn txt xde xdr xdt xed xee xen xer xet xex xrd xrt xrx xtr xtx xxx