a-a a-b a-c a-t aaa aab aac aat aay ab- aba abb abc abt aby ac- aca acb acc act acy at- ata atb atc att ay- aya ayc ayt baa bab bac bat bay bba bbb bbc bbt bby bca bcb bcc bct bcy bta btb btc btt bty by- bya byc byt c-- caa cab cac cat cay cba cbb cbc cbt cby cca ccb ccc cct cta ctb ctc ctt cty cya cyb cyc cyt taa tab tac tat tay tba tbb tbc tbt tca tcb tcc tct tta ttb ttc ttt tty tya tyc tyt yaa yab yac yat yay ybc yby yca ycc ycy yta ytc ytt yyb yyc yyt yyy