a-a a-b a-t a-z aaa aab aad aat aaz ab- aba abb abd abt abz ad- ada adb add adt adz at- ata atb atd att atz az- aza azb azd azt azz baa bab bad bat baz bba bbb bbd bbt bda bdb bdd bdt bdz bta btb btd btt btz bza bzd bzz daa dab dad dat daz dba dbb dbd dbt dbz dda ddb ddd ddt ddz dta dtb dtd dtt dtz dza dzb dzd taa tab tad tat taz tba tbb tbd tbt tbz tda tdb tdd tdt tta ttb ttd ttt tza tzd zaa zab zad zat zaz zbb zbt zdt zta zzt zzz