a-a a-c a-t a-z aaa aac aan aat aaz ac- aca acc acn act acz an- ana anc ann ant anz at- ata atc atn att atz az- aza azn azt azz c-- caa cac can cat caz cca ccc ccn cct ccz cn- cna cnc cnn cnt cta ctc ctn ctt ctz cz- czc czt naa nac nan nat naz nca ncc ncn nct nna nnc nnn nnt nnz nta ntc ntn ntt ntz nzz taa tac tan tat taz tca tcc tcn tct tna tnc tnn tnt tnz tta ttc ttn ttt tza zaa zac zan zat zaz znc znn zta zzt zzz