a-a a-c a-t aaa aac aae aan aat aax ac- aca acc ace acn act acx aea aec aee aen aet aex an- ana anc ane ann ant anx at- ata atc ate atn att atx ax- axa axe axn axt axx c-- caa cac cae can cat cax cca ccc cce ccn cct ccx ce- cea cec cee cen cet cex cn- cna cnc cne cnn cnt cnx cta ctc cte ctn ctt ctx cxc cxt cxx eaa eac eae ean eat eax ec- eca ecc ece ecn ect ecx eea eec eee een eet eex en- ena enc ene enn ent eta etc ete etn ett etx ex- exa exc exe ext exx naa nac nae nan nat nax nca ncc nce ncn nct ncx ne- nea nec nee nen net nex nna nnc nne nnn nnt nta ntc nte ntn ntt ntx nxc nxt t-x taa tac tae tan tat tax tca tcc tce tcn tct tcx te- tea tec tee ten tet tex tna tnc tne tnn tnt tnx tta ttc tte ttn ttt ttx txe txn txt xaa xac xan xat xcx xee xen xet xex xna xnc xtc xtx xxx