a-a a-b a-c a-z aaa aab aac aam aaz ab- aba abb abc abm abz ac- aca acb acc acm acz ama amb amc amm amz az- aza azb azm azz baa bab bac bam baz bba bbb bbc bbm bca bcb bcc bcm bcz bma bmb bmc bmm bmz bza bzz c-- caa cab cac cam caz cba cbb cbc cbm cbz cca ccb ccc ccm ccz cma cmb cmc cmm cz- czc czm maa mab mac mam maz mba mbb mbc mbm mc- mca mcb mcc mcm mcz mma mmb mmc mmm mmz mza mzb mzm zaa zab zac zam zaz zbb zbc zbm zma zmb zmc zmm zzz