-er ddd dde ddi ddr ddt ddx de- ded dee dei der det dex di- did die dii dir dit dix drd dre dri drr drt drx dtd dte dti dtr dtt dtx dxd dxi dxr dxt dxx ed- edd ede edi edr edt edx eed eee eer eet eex eid eie eii eir eit eix erd ere eri err ert etd ete eti etr ett etx ex- exd exe exi exr ext exx i-d idd ide idi idr idt idx ie- ied iee iei ier iet iex iid iie iii iir iit iix ir- ird ire iri irr irt irx itd ite iti itt itx ixe ixi rdd rde rdi rdr rdt rdx re- red ree rei rer ret rex rid rie rii rir rit rix rrd rri rrr rrt rtd rte rti rtr rtt rtx rxr t-x tdd tde tdi tdr tdt tdx te- ted tee tei ter tet tex tid tie tii tir tit tix trd tre tri trr trt trx ttd tte tti ttr ttt ttx txe txi txt xde xdi xdr xdt xed xee xer xet xex xie xii xit xix xrd xrt xrx xti xtr xtx xxi xxx