a-a a-b a-c a-z aaa aab aac aae aau aaz ab- aba abb abc abe abu abz ac- aca acb acc ace acu acz aea aeb aec aee aeu aez au- aua aub auc aue auz az- aza azb aze azu azz b-u baa bab bac bae bau baz bba bbb bbc bbe bbu bca bcb bcc bce bcu bcz be- bea beb bec bee beu bez bua bub buc bue buu buz bza bze bzu bzz c-- caa cab cac cae cau caz cba cbb cbc cbe cbu cbz cca ccb ccc cce ccu ccz ce- cea ceb cec cee ceu cez cua cub cuc cue cuu cuz cz- czc cze eaa eab eac eae eau eaz eba ebb ebc ebe ebu ec- eca ecb ecc ece ecu eea eeb eec eee eu- eua eub euc eue eze ezz ua- uaa uab uac uae uau uaz uba ubb ubc ube ubu uca ucb ucc uce ucu uea ueb uec uee uua uuc uue uuu uza uzb uzu zaa zab zac zaz zbb zbc zce zea zeb zec zee zez zub zuc zuz zzz