a-a a-t aaa aae aaf aat aax aea aee aef aet aex af- afa afe aff aft afx at- ata ate atf att atx ax- axa axe axt axx eaa eae eaf eat eax eea eee eef eet eex ef- efa efe eff eft efx eta ete etf ett etx ex- exa exe ext exx faa fae faf fat fax fea fee fef fet fex ffa ffe fff fft ffx fta fte ftf ftt ftx fxe fxt fxx t-x taa tae taf tat tax te- tea tee tef tet tex tfa tfe tff tft tfx tta tte ttf ttt ttx txe txf txt xaa xaf xat xee xet xex xfa xfe xft xfx xtf xtx xxx