a-a a-b a-t a-z aaa aab aat aau aaz ab- aba abb abt abu abz at- ata atb att atu atz au- aua aub aut auz az- aza azb azt azu azz b-u baa bab bat bau baz bba bbb bbt bbu bta btb btt btu btz bua bub but buu buz bza bzu bzz taa tab tat tau taz tba tbb tbt tbu tbz tta ttb ttt ttu tua tub tut tuu tuz tza tzu ua- uaa uab uat uau uaz uba ubb ubt ubu uta utb utt utu utz uua uut uuu uza uzb uzu zaa zab zat zaz zbb zbt zta zub zut zuz zzt zzz