a-a a-b a-i a-t aaa aab aae aai aat aax ab- aba abb abe abi abt abx aea aeb aee aei aet aex ai- aia aib aie aii ait aix at- ata atb ate ati att atx ax- axa axe axi axt axx baa bab bae bai bat bax bba bbb bbe bbi bbt bbx be- bea beb bee bei bet bex bi- bia bib bie bii bit bix bta btb bte bti btt btx bxb bxi bxx eaa eab eae eai eat eax eba ebb ebe ebi ebt ebx eea eeb eee eet eex eia eib eie eii eit eix eta etb ete eti ett etx ex- exa exe exi ext exx ia- iaa iab iae iai iat iba ibb ibe ibi ibt ibx ie- iea iee iei iet iex iia iib iie iii iit iix ita itb ite iti itt itx ixe ixi t-x taa tab tae tai tat tax tba tbb tbe tbi tbt te- tea teb tee tei tet tex tia tib tie tii tit tix tta ttb tte tti ttt ttx txe txi txt xaa xat xbe xbx xee xet xex xia xie xii xit xix xti xtx xxi xxx