a-a a-b a-c aaa aab aac aag aay ab- aba abb abc abg aby ac- aca acb acc acg acy ag- aga agb agc agg agy ay- aya ayc baa bab bac bag bay bba bbb bbc bbg bby bca bcb bcc bcg bcy bga bgb bgc bgg by- bya byc byg c-- caa cab cac cag cay cba cbb cbc cbg cby cca ccb ccc ccg cga cgb cgc cgg cgy cya cyb cyc cyg gaa gab gac gag gay gba gbc gbg gby gca gcb gcc gcg gga ggb ggc ggg gy- gya gyb yaa yab yac yag yay ybc ybg yby yca ycc ycy yga ygc yyb yyc yyg yyy