a-a a-b a-c aaa aab aac aan aay ab- aba abb abc abn aby ac- aca acb acc acn acy an- ana anb anc ann any ay- aya ayc ayn baa bab bac ban bay bba bbb bbc bbn bby bca bcb bcc bcn bcy bna bnb bnc bnn by- bya byc byn c-- caa cab cac can cay cba cbb cbc cbn cby cca ccb ccc ccn cn- cna cnb cnc cnn cny cya cyb cyc cyn naa nab nac nan nay nba nbb nbc nbn nca ncb ncc ncn nna nnb nnc nnn nya nyc nyn nyy yaa yab yac yan yay ybc yby yca ycc ycy yna ynn yny yyb yyc yyy