a-a a-b aaa aab aad aaf aam ab- aba abb abd abf abm ad- ada adb add adf adm af- afa afb afd aff afm ama amb amd amf amm baa bab bad baf bam bba bbb bbd bbf bbm bda bdb bdd bdf bdm bfa bfb bfd bff bfm bma bmb bmd bmf bmm daa dab dad daf dam dba dbb dbd dbf dbm dda ddb ddd ddf ddm dfa dfb dfd dff dfm dma dmb dmd dmf dmm faa fab fad faf fam fba fbb fbd fbf fbm fda fdb fdd fdf fdm ffa ffd fff ffm fma fmb fmd fmf fmm m-f maa mab mad maf mam mba mbb mbd mbf mbm mda mdb mdd mdf mdm mfa mfb mfd mff mfm mma mmb mmd mmf mmm