-er a-a a-b aaa aab aad aae aao aar aax ab- aba abb abd abe abo abr abx ad- ada adb add ade ado adr adx aea aeb aed aee aeo aer aex aoa aob aod aoe aoo aor aox ar- ara arb ard are aro arr arx ax- axa axe axo axr axx baa bab bad bae bao bar bax bba bbb bbd bbe bbo bbr bbx bda bdb bdd bde bdo bdr bdx be- bea beb bed bee beo ber bex boa bob bod boe boo bor box bra brb brd bre bro brr brx bxb bxd bxo bxx daa dab dad dae dao dar dax dba dbb dbd dbe dbo dbr dbx dda ddb ddd dde ddo ddr ddx de- dea deb ded dee deo der dex doa dob dod doe doo dor dox dra drb drd dre dro drr drx dxd dxo dxr dxx eaa eab ead eae eao ear eax eba ebb ebd ebe ebo ebr ebx ed- eda edb edd ede edo edr edx eea eeb eed eee eeo eer eex eo- eoa eob eod eoe eoo eor era erb erd ere ero err ex- exa exd exe exo exr exx oaa oab oad oae oao oar oax ob- oba obb obd obe obo obr obx oda odb odd ode odo odr oea oeb oed oee oeo oer oex oo- ooa oob ood ooo oor oox or- ora orb ord ore oro orr orx ox- oxa oxb oxo oxx ra- raa rab rad rae rao rar rax rba rbb rbd rbe rbo rbr rbx rda rdb rdd rde rdo rdr rdx re- rea reb red ree reo rer rex roa rob rod roe roo ror rox rra rrb rrd rrr rxr xaa xad xar xbe xbr xbx xda xdb xde xdr xed xee xer xex xoa xod xoo xor xox xrd xrx xxo xxx