a-a a-b a-z aaa aab aae aam aaz ab- aba abb abe abm abz aea aeb aee aem aez ama amb ame amm amz az- aza azb aze azm azz baa bab bae bam baz bba bbb bbe bbm be- bea beb bee bem bez bma bmb bme bmm bmz bza bze bzz eaa eab eae eam eaz eba ebb ebe ebm eea eeb eee eem em- ema emb eme emm eze ezz maa mab mae mam maz mba mbb mbe mbm mea meb mee mem mez mma mmb mme mmm mmz mza mzb mzm zaa zab zam zaz zbb zbm zea zeb zee zem zez zma zmb zmm zzz