-er -th ddd dde ddh ddr ddt ddx de- ded dee deh der det dex dh- dhd dhe dhh dhr dht drd dre drr drt drx dtd dte dth dtr dtt dtx dxd dxr dxt dxx ed- edd ede edh edr edt edx eed eee eer eet eex ehd ehe ehh ehr eht erd ere erh err ert etd ete eth etr ett etx ex- exd exe exh exr ext exx hdd hde hdh hdr hdt hdx he- hed hee heh her het hex hhd hhe hhh hhr hht hr- hrd hre hrh hrr hrt htd hte hth htr htt htx hxd rdd rde rdh rdr rdt rdx re- red ree reh rer ret rex rh- rhd rhe rhh rhr rht rrd rrh rrr rrt rtd rte rtr rtt rtx rxr t-x tdd tde tdh tdr tdt tdx te- ted tee teh ter tet tex th- thd the thh thr tht thx trd tre trh trr trt trx ttd tte tth ttr ttt ttx txe txt xde xdh xdr xdt xed xee xer xet xex xhd xht xrd xrt xrx xtr xtx xxx