a-a a-c a-t aaa aac aae aat aax ac- aca acc ace act acx aea aec aee aet aex at- ata atc ate att atx ax- axa axe axt axx c-- caa cac cae cat cax cca ccc cce cct ccx ce- cea cec cee cet cex cta ctc cte ctt ctx cxc cxt cxx eaa eac eae eat eax ec- eca ecc ece ect ecx eea eec eee eet eex eta etc ete ett etx ex- exa exc exe ext exx t-x taa tac tae tat tax tca tcc tce tct tcx te- tea tec tee tet tex tta ttc tte ttt ttx txe txt xaa xac xat xcx xee xet xex xtc xtx xxx