a-a a-b a-t aaa aab aad aat aay ab- aba abb abd abt aby ad- ada adb add adt ady at- ata atb atd att ay- aya ayd ayt baa bab bad bat bay bba bbb bbd bbt bby bda bdb bdd bdt bdy bta btb btd btt bty by- bya byd byt daa dab dad dat day dba dbb dbd dbt dby dda ddb ddd ddt ddy dta dtb dtd dtt dty dy- dya dyb dyd dyy taa tab tad tat tay tba tbb tbd tbt tda tdb tdd tdt tdy tta ttb ttd ttt tty tya tyd tyt yaa yab yad yat yay yby yda ydt ydy yta ytd ytt yyb yyt yyy