a-a a-b aaa aab aak aam aan aao ab- aba abb abk abm abn abo aka akb akk akm akn ako ama amb amk amm amn amo an- ana anb ank anm ann ano aoa aob aok aom aon aoo baa bab bak bam ban bao bba bbb bbk bbm bbn bbo bka bkb bkk bkm bkn bko bma bmb bmk bmm bmn bmo bna bnb bnk bnn bno boa bob bok bom bon boo ka- kaa kab kak kam kan kao kba kbb kbk kbm kbn kbo kkb kkk kkm kkn kma kmb kmk kmm kmo kn- kna knk knm knn kno koa kob kok kom kon koo m-o maa mab mak mam man mao mba mbb mbk mbm mbo mka mkb mkk mkm mkn mko mma mmb mmk mmm mmn mmo mna mnb mnk mnm mnn mno moa mob mok mom mon moo naa nab nak nam nan nao nba nbb nbk nbm nbn nbo nka nkk nkm nkn nko nma nmb nmk nmm nmn nmo nna nnb nnk nnm nnn nno no- noa nob nok nom non noo oaa oab oak oam oan oao ob- oba obb obk obm obn obo oka okb okk oko om- oma omb omm omn omo on- ona onb onk onn ono oo- ooa oob ook oom oon ooo