a-a a-b a-c aaa aab aac aam aan ab- aba abb abc abm abn ac- aca acb acc acm acn ama amb amc amm amn an- ana anb anc anm ann baa bab bac bam ban bba bbb bbc bbm bbn bca bcb bcc bcm bcn bma bmb bmc bmm bmn bna bnb bnc bnn c-- caa cab cac cam can cba cbb cbc cbm cbn cca ccb ccc ccm ccn cma cmb cmc cmm cmn cn- cna cnb cnc cnm cnn maa mab mac mam man mba mbb mbc mbm mc- mca mcb mcc mcm mcn mma mmb mmc mmm mmn mna mnb mnc mnm mnn naa nab nac nam nan nba nbb nbc nbm nbn nca ncb ncc ncm ncn nma nmb nmc nmm nmn nna nnb nnc nnm nnn