-er ddd dde ddi ddr ddx de- ded dee dei der dex di- did die dii dir dix drd dre dri drr drx dxd dxi dxr dxx ed- edd ede edi edr edx eed eee eer eex eid eie eii eir eix erd ere eri err ex- exd exe exi exr exx i-d idd ide idi idr idx ie- ied iee iei ier iex iid iie iii iir iix ir- ird ire iri irr irx ixe ixi rdd rde rdi rdr rdx re- red ree rei rer rex rid rie rii rir rix rrd rri rrr rxr xde xdi xdr xed xee xer xex xie xii xix xrd xrx xxi xxx