-er a-a a-b aaa aab aad aae aao aar aau aax ab- aba abb abd abe abo abr abu abx ad- ada adb add ade ado adr adu adx aea aeb aed aee aeo aer aeu aex aoa aob aod aoe aoo aor aou aox ar- ara arb ard are aro arr aru arx au- aua aub aud aue auo aur aux ax- axa axe axo axr axx b-u baa bab bad bae bao bar bau bax bba bbb bbd bbe bbo bbr bbu bbx bda bdb bdd bde bdo bdr bdu bdx be- bea beb bed bee beo ber beu bex boa bob bod boe boo bor bou box bra brb brd bre bro brr bru brx bua bub bud bue buo bur buu bux bxb bxd bxo bxx daa dab dad dae dao dar dau dax dba dbb dbd dbe dbo dbr dbu dbx dda ddb ddd dde ddo ddr ddu ddx de- dea deb ded dee deo der deu dex doa dob dod doe doo dor dou dox dra drb drd dre dro drr dru drx dua dub dud due duo dur dux dxd dxo dxr dxx eaa eab ead eae eao ear eau eax eba ebb ebd ebe ebo ebr ebu ebx ed- eda edb edd ede edo edr edu edx eea eeb eed eee eeo eer eex eo- eoa eob eod eoe eoo eor eou era erb erd ere ero err eru eu- eua eub eud eue eur eux ex- exa exd exe exo exr exu exx oaa oab oad oae oao oar oau oax ob- oba obb obd obe obo obr obu obx oda odb odd ode odo odr odu oea oeb oed oee oeo oer oex oo- ooa oob ood ooo oor oox or- ora orb ord ore oro orr oru orx ou- oua oud oue ouo our ox- oxa oxb oxo oxx ra- raa rab rad rae rao rar rau rax rba rbb rbd rbe rbo rbr rbu rbx rda rdb rdd rde rdo rdr rdu rdx re- rea reb red ree reo rer reu rex roa rob rod roe roo ror rou rox rra rrb rrd rrr rru rua rub rud rue ruo rur ruu rux rxr ua- uaa uab uad uae uao uar uau uba ubb ube ubo ubr ubu ubx uda udb udd ude udo udr udu udx uea ueb ued uee uer uoa uob uod uoe uoo uor uox ur- ura urb urd ure uro urr uru urx uua uue uur uuu uxb uxo uxr uxu xaa xad xar xau xbe xbr xbx xda xdb xde xdr xed xee xer xeu xex xoa xod xoo xor xox xrd xrx xue xxo xxx