a-a a-c a-t a-z aaa aac aar aat aaz ac- aca acc acr act acz ar- ara arc arr art arz at- ata atc atr att atz az- aza azt azz c-- caa cac car cat caz cca ccc ccr cct ccz cra crc crr crt crz cta ctc ctr ctt ctz cz- czc czt ra- raa rac rar rat raz rca rcc rcr rct rra rrc rrr rrt rta rtc rtr rtt rtz rza taa tac tar tat taz tca tcc tcr tct tra trc trr trt trz tta ttc ttr ttt tza zaa zac zar zat zaz zta ztr zzr zzt zzz