a-a a-c a-t aaa aac aad aan aat ac- aca acc acd acn act ad- ada adc add adn adt an- ana anc and ann ant at- ata atc atd atn att c-- caa cac cad can cat cca ccc ccd ccn cct cda cdc cdd cdn cdt cn- cna cnc cnd cnn cnt cta ctc ctd ctn ctt daa dac dad dan dat dca dcc dcd dcn dct dda ddc ddd ddn ddt dna dnc dnd dnn dnt dta dtc dtd dtn dtt naa nac nad nan nat nca ncc ncd ncn nct nda ndc ndd ndn ndt nna nnc nnn nnt nta ntc ntd ntn ntt taa tac tad tan tat tca tcc tcd tcn tct tda tdc tdd tdn tdt tna tnc tnd tnn tnt tta ttc ttd ttn ttt