-er ddd dde ddp ddr ddt ddx de- ded dee dep der det dex dpd dpe dpp dpr dpt drd dre drp drr drt drx dtd dte dtp dtr dtt dtx dxd dxp dxr dxt dxx ed- edd ede edp edr edt edx eed eee eep eer eet eex ep- epd epe epp epr ept epx erd ere erp err ert etd ete etp etr ett etx ex- exd exe exp exr ext exx p-p pdd pde pdp pdr pdt pdx ped pee pep per pet pex ppd ppe ppp ppr ppt ppx prd pre prp prr prt prx pt- ptd pte ptp ptr ptt ptx pxe pxr pxt rdd rde rdp rdr rdt rdx re- red ree rep rer ret rex rpd rpe rpp rpr rpt rpx rrd rrp rrr rrt rtd rte rtp rtr rtt rtx rxp rxr t-x tdd tde tdp tdr tdt tdx te- ted tee tep ter tet tex tpd tpe tpp tpr tpt tpx trd tre trp trr trt trx ttd tte ttp ttr ttt ttx txe txt xde xdr xdt xed xee xep xer xet xex xpd xpe xpp xpt xrd xrt xrx xtp xtr xtx xxp xxx