a-a a-c a-t aaa aac aan aas aat ac- aca acc acn acs act an- ana anc ann ans ant as- asa asc asn ass ast at- ata atc atn ats att c-- caa cac can cas cat cca ccc ccn ccs cct cn- cna cnc cnn cns cnt csa csc csn css cst cta ctc ctn cts ctt naa nac nan nas nat nca ncc ncn ncs nct nna nnc nnn nns nnt nsa nsc nsn nss nst nta ntc ntn nts ntt saa sac san sas sat sca scc scn scs sct sna snc snn sns snt ss- ssa ssc ssn sss sst sta stc stn sts stt taa tac tan tas tat tca tcc tcn tcs tct tna tnc tnn tns tnt tsa tsc tsn tss tst tta ttc ttn tts ttt