a-a a-b a-t aaa aab aae aao aas aat aax ab- aba abb abe abo abs abt abx aea aeb aee aeo aes aet aex aoa aob aoe aoo aos aot aox as- asa asb ase aso ass ast asx at- ata atb ate ato ats att atx ax- axa axe axo axs axt axx baa bab bae bao bas bat bax bba bbb bbe bbo bbs bbt bbx be- bea beb bee beo bes bet bex boa bob boe boo bos bot box bsa bsb bse bso bss bst bsx bta btb bte bto bts btt btx bxb bxo bxx eaa eab eae eao eas eat eax eba ebb ebe ebo ebs ebt ebx eea eeb eee eeo ees eet eex eo- eoa eob eoe eoo eos eot es- esa esb ese eso ess est esx eta etb ete eto ets ett etx ex- exa exe exo exs ext exx oaa oab oae oao oas oat oax ob- oba obb obe obo obs obt obx oea oeb oee oeo oes oet oex oo- ooa oob ooo oos oot oox os- osa osb ose oso oss ost osx ot- ota otb ote oto ots ott ox- oxa oxb oxo oxt oxx saa sab sae sao sas sat sax sba sbb sbe sbo sbs sbt sbx se- sea seb see seo ses set sex soa sob soe soo sos sot sox ss- ssa ssb sse sso sss sst ssx sta stb ste sto sts stt stx sxs sxt t-x taa tab tae tao tas tat tax tba tbb tbe tbo tbs tbt te- tea teb tee teo tes tet tex to- toa tob toe too tos tot tox tsa tsb tse tso tss tst tsx tta ttb tte tto tts ttt ttx txe txs txt xaa xas xat xbe xbx xee xes xet xex xoa xoo xos xot xox xsa xsb xss xst xts xtx xxo xxx