a-a a-b a-c a-z aaa aab aac aan aau aaz ab- aba abb abc abn abu abz ac- aca acb acc acn acu acz an- ana anb anc ann anu anz au- aua aub auc aun auz az- aza azb azn azu azz b-u baa bab bac ban bau baz bba bbb bbc bbn bbu bca bcb bcc bcn bcu bcz bna bnb bnc bnn bnu bnz bua bub buc bun buu buz bza bzn bzu bzz c-- caa cab cac can cau caz cba cbb cbc cbn cbu cbz cca ccb ccc ccn ccu ccz cn- cna cnb cnc cnn cnu cua cub cuc cun cuu cuz cz- czc naa nab nac nan nau naz nba nbb nbc nbn nbu nca ncb ncc ncn ncu nna nnb nnc nnn nnu nnz nua nub nuc nun nuu nzb nzz ua- uaa uab uac uan uau uaz uba ubb ubc ubn ubu uca ucb ucc ucn ucu un- una unb unc unn unu uua uuc uun uuu uza uzb uzu zaa zab zac zan zaz zbb zbc znc znn zub zuc zun zuz zzz