a-a a-b a-i a-t aaa aab aae aai aas aat aax ab- aba abb abe abi abs abt abx aea aeb aee aei aes aet aex ai- aia aib aie aii ais ait aix as- asa asb ase asi ass ast asx at- ata atb ate ati ats att atx ax- axa axe axi axs axt axx baa bab bae bai bas bat bax bba bbb bbe bbi bbs bbt bbx be- bea beb bee bei bes bet bex bi- bia bib bie bii bis bit bix bsa bsb bse bsi bss bst bsx bta btb bte bti bts btt btx bxb bxi bxx eaa eab eae eai eas eat eax eba ebb ebe ebi ebs ebt ebx eea eeb eee ees eet eex eia eib eie eii eis eit eix es- esa esb ese esi ess est esx eta etb ete eti ets ett etx ex- exa exe exi exs ext exx ia- iaa iab iae iai ias iat iba ibb ibe ibi ibs ibt ibx ie- iea iee iei ies iet iex iia iib iie iii iis iit iix is- isa isb ise isi iss ist ita itb ite iti its itt itx ixe ixi saa sab sae sai sas sat sax sba sbb sbe sbi sbs sbt sbx se- sea seb see sei ses set sex sia sib sie sii sis sit six ss- ssa ssb sse ssi sss sst ssx sta stb ste sti sts stt stx sxi sxs sxt t-x taa tab tae tai tas tat tax tba tbb tbe tbi tbs tbt te- tea teb tee tei tes tet tex tia tib tie tii tis tit tix tsa tsb tse tsi tss tst tsx tta ttb tte tti tts ttt ttx txe txi txs txt xaa xas xat xbe xbx xee xes xet xex xia xie xii xis xit xix xsa xsb xsi xss xst xti xts xtx xxi xxx