a-a a-b aaa aab aae aaf aam aao ab- aba abb abe abf abm abo aea aeb aee aef aem aeo af- afa afb afe aff afm afo ama amb ame amf amm amo aoa aob aoe aof aom aoo baa bab bae baf bam bao bba bbb bbe bbf bbm bbo be- bea beb bee bef bem beo bfa bfb bfe bff bfm bfo bma bmb bme bmf bmm bmo boa bob boe bof bom boo eaa eab eae eaf eam eao eba ebb ebe ebf ebm ebo eea eeb eee eef eem eeo ef- efa efb efe eff efm efo em- ema emb eme emf emm emo eo- eoa eob eoe eof eom eoo faa fab fae faf fam fao fba fbb fbe fbf fbm fbo fea feb fee fef fem feo ffa ffe fff ffm ffo fma fmb fme fmf fmm fmo foa fob foe fof fom foo m-f m-o maa mab mae maf mam mao mba mbb mbe mbf mbm mbo mea meb mee mef mem meo mfa mfb mfe mff mfm mfo mma mmb mme mmf mmm mmo moa mob moe mof mom moo oaa oab oae oaf oam oao ob- oba obb obe obf obm obo oea oeb oee oef oem oeo of- ofa ofb ofe off ofm ofo om- oma omb ome omf omm omo oo- ooa oob oof oom ooo