-er a-a a-b a-t aaa aab aad aae aao aar aat aax ab- aba abb abd abe abo abr abt abx ad- ada adb add ade ado adr adt adx aea aeb aed aee aeo aer aet aex aoa aob aod aoe aoo aor aot aox ar- ara arb ard are aro arr art arx at- ata atb atd ate ato atr att atx ax- axa axe axo axr axt axx baa bab bad bae bao bar bat bax bba bbb bbd bbe bbo bbr bbt bbx bda bdb bdd bde bdo bdr bdt bdx be- bea beb bed bee beo ber bet bex boa bob bod boe boo bor bot box bra brb brd bre bro brr brt brx bta btb btd bte bto btr btt btx bxb bxd bxo bxx daa dab dad dae dao dar dat dax dba dbb dbd dbe dbo dbr dbt dbx dda ddb ddd dde ddo ddr ddt ddx de- dea deb ded dee deo der det dex doa dob dod doe doo dor dot dox dra drb drd dre dro drr drt drx dta dtb dtd dte dto dtr dtt dtx dxd dxo dxr dxt dxx eaa eab ead eae eao ear eat eax eba ebb ebd ebe ebo ebr ebt ebx ed- eda edb edd ede edo edr edt edx eea eeb eed eee eeo eer eet eex eo- eoa eob eod eoe eoo eor eot era erb erd ere ero err ert eta etb etd ete eto etr ett etx ex- exa exd exe exo exr ext exx oaa oab oad oae oao oar oat oax ob- oba obb obd obe obo obr obt obx oda odb odd ode odo odr odt oea oeb oed oee oeo oer oet oex oo- ooa oob ood ooo oor oot oox or- ora orb ord ore oro orr ort orx ot- ota otb otd ote oto otr ott ox- oxa oxb oxo oxt oxx ra- raa rab rad rae rao rar rat rax rba rbb rbd rbe rbo rbr rbt rbx rda rdb rdd rde rdo rdr rdt rdx re- rea reb red ree reo rer ret rex roa rob rod roe roo ror rot rox rra rrb rrd rrr rrt rta rtb rtd rte rto rtr rtt rtx rxr t-x taa tab tad tae tao tar tat tax tba tbb tbd tbe tbo tbr tbt tda tdb tdd tde tdo tdr tdt tdx te- tea teb ted tee teo ter tet tex to- toa tob tod toe too tor tot tox tra trb trd tre tro trr trt trx tta ttb ttd tte tto ttr ttt ttx txe txt xaa xad xar xat xbe xbr xbx xda xdb xde xdr xdt xed xee xer xet xex xoa xod xoo xor xot xox xrd xrt xrx xtr xtx xxo xxx