-er a-a a-b a-i a-t aaa aab aae aai aao aar aas aat aax ab- aba abb abe abi abo abr abs abt abx aea aeb aee aei aeo aer aes aet aex ai- aia aib aie aii aio air ais ait aix aoa aob aoe aoi aoo aor aos aot aox ar- ara arb are ari aro arr ars art arx as- asa asb ase asi aso asr ass ast asx at- ata atb ate ati ato atr ats att atx ax- axa axe axi axo axr axs axt axx baa bab bae bai bao bar bas bat bax bba bbb bbe bbi bbo bbr bbs bbt bbx be- bea beb bee bei beo ber bes bet bex bi- bia bib bie bii bio bir bis bit bix boa bob boe boi boo bor bos bot box bra brb bre bri bro brr brs brt brx bsa bsb bse bsi bso bsr bss bst bsx bta btb bte bti bto btr bts btt btx bxb bxi bxo bxx eaa eab eae eai eao ear eas eat eax eba ebb ebe ebi ebo ebr ebs ebt ebx eea eeb eee eeo eer ees eet eex eia eib eie eii eio eir eis eit eix eo- eoa eob eoe eoi eoo eor eos eot era erb ere eri ero err ers ert es- esa esb ese esi eso esr ess est esx eta etb ete eti eto etr ets ett etx ex- exa exe exi exo exr exs ext exx ia- iaa iab iae iai iao iar ias iat iba ibb ibe ibi ibo ibr ibs ibt ibx ie- iea iee iei ier ies iet iex iia iib iie iii iio iir iis iit iix io- ioa iob ioe ioi ioo ior ios iot ir- ira irb ire iri iro irr irs irt irx is- isa isb ise isi iso isr iss ist ita itb ite iti ito its itt itx ixe ixi o-i oaa oab oae oai oao oar oas oat oax ob- oba obb obe obi obo obr obs obt obx oea oeb oee oei oeo oer oes oet oex oia oib oie oii oio oir ois oit oo- ooa oob ooi ooo oor oos oot oox or- ora orb ore ori oro orr ors ort orx os- osa osb ose osi oso osr oss ost osx ot- ota otb ote oti oto otr ots ott ox- oxa oxb oxi oxo oxt oxx ra- raa rab rae rai rao rar ras rat rax rba rbb rbe rbi rbo rbr rbs rbt rbx re- rea reb ree rei reo rer res ret rex ria rib rie rii rio rir ris rit rix roa rob roe roi roo ror ros rot rox rra rrb rri rrr rrs rrt rsa rsb rse rsi rso rsr rss rst rsx rta rtb rte rti rto rtr rts rtt rtx rxr rxs saa sab sae sai sao sar sas sat sax sba sbb sbe sbi sbo sbr sbs sbt sbx se- sea seb see sei seo ser ses set sex sia sib sie sii sio sir sis sit six soa sob soe soi soo sor sos sot sox sr- sra srb sre sri sro srr srs srt srx ss- ssa ssb sse ssi sso ssr sss sst ssx sta stb ste sti sto str sts stt stx sxi sxs sxt t-x taa tab tae tai tao tar tas tat tax tba tbb tbe tbi tbo tbr tbs tbt te- tea teb tee tei teo ter tes tet tex tia tib tie tii tio tir tis tit tix to- toa tob toe toi too tor tos tot tox tra trb tre tri tro trr trs trt trx tsa tsb tse tsi tso tsr tss tst tsx tta ttb tte tti tto ttr tts ttt ttx txe txi txs txt xaa xar xas xat xbe xbr xbx xee xer xes xet xex xia xie xii xio xis xit xix xoa xoi xoo xor xos xot xox xrt xrx xsa xsb xsi xss xst xti xtr xts xtx xxi xxo xxx