a-a a-b a-c aaa aab aac aak aam aan aao ab- aba abb abc abk abm abn abo ac- aca acb acc ack acm acn aco aka akb akc akk akm akn ako ama amb amc amk amm amn amo an- ana anb anc ank anm ann ano aoa aob aoc aok aom aon aoo baa bab bac bak bam ban bao bba bbb bbc bbk bbm bbn bbo bca bcb bcc bck bcm bcn bco bka bkb bkc bkk bkm bkn bko bma bmb bmc bmk bmm bmn bmo bna bnb bnc bnk bnn bno boa bob boc bok bom bon boo c-- caa cab cac cak cam can cao cba cbb cbc cbk cbm cbn cbo cca ccb ccc cck ccm ccn cco cka ckb ckc ckm cko cma cmb cmc cmk cmm cmn cmo cn- cna cnb cnc cnm cnn cno co- coa cob coc cok com con coo ka- kaa kab kac kak kam kan kao kba kbb kbc kbk kbm kbn kbo kca kcb kcc kck kcm kcn kkb kkc kkk kkm kkn kma kmb kmc kmk kmm kmo kn- kna knc knk knm knn kno koa kob koc kok kom kon koo m-o maa mab mac mak mam man mao mba mbb mbc mbk mbm mbo mc- mca mcb mcc mck mcm mcn mco mka mkb mkc mkk mkm mkn mko mma mmb mmc mmk mmm mmn mmo mna mnb mnc mnk mnm mnn mno moa mob moc mok mom mon moo naa nab nac nak nam nan nao nba nbb nbc nbk nbm nbn nbo nca ncb ncc nck ncm ncn nco nka nkc nkk nkm nkn nko nma nmb nmc nmk nmm nmn nmo nna nnb nnc nnk nnm nnn nno no- noa nob noc nok nom non noo oaa oab oac oak oam oan oao ob- oba obb obc obk obm obn obo oc- oca ocb occ ock ocm ocn oco oka okb okc okk oko om- oma omb omc omm omn omo on- ona onb onc onk onn ono oo- ooa oob ooc ook oom oon ooo