a-a a-c a-t aaa aac aad aar aat ac- aca acc acd acr act ad- ada adc add adr adt ar- ara arc ard arr art at- ata atc atd atr att c-- caa cac cad car cat cca ccc ccd ccr cct cda cdc cdd cdr cdt cra crc crd crr crt cta ctc ctd ctr ctt daa dac dad dar dat dca dcc dcd dcr dct dda ddc ddd ddr ddt dra drc drd drr drt dta dtc dtd dtr dtt ra- raa rac rad rar rat rca rcc rcd rcr rct rda rdc rdd rdr rdt rra rrc rrd rrr rrt rta rtc rtd rtr rtt taa tac tad tar tat tca tcc tcd tcr tct tda tdc tdd tdr tdt tra trc trd trr trt tta ttc ttd ttr ttt