-er bbb bbd bbe bbi bbr bbx bdb bdd bde bdi bdr bdx be- beb bed bee bei ber bex bi- bib bid bie bii bir bix brb brd bre bri brr brx bxb bxd bxi bxx dbb dbd dbe dbi dbr dbx ddb ddd dde ddi ddr ddx de- deb ded dee dei der dex di- dib did die dii dir dix drb drd dre dri drr drx dxd dxi dxr dxx ebb ebd ebe ebi ebr ebx ed- edb edd ede edi edr edx eeb eed eee eer eex eib eid eie eii eir eix erb erd ere eri err ex- exd exe exi exr exx i-d ibb ibd ibe ibi ibr ibx idb idd ide idi idr idx ie- ied iee iei ier iex iib iid iie iii iir iix ir- irb ird ire iri irr irx ixe ixi rbb rbd rbe rbi rbr rbx rdb rdd rde rdi rdr rdx re- reb red ree rei rer rex rib rid rie rii rir rix rrb rrd rri rrr rxr xbe xbr xbx xdb xde xdi xdr xed xee xer xex xie xii xix xrd xrx xxi xxx