a-a a-b a-c aaa aab aac aam aan aao ab- aba abb abc abm abn abo ac- aca acb acc acm acn aco ama amb amc amm amn amo an- ana anb anc anm ann ano aoa aob aoc aom aon aoo baa bab bac bam ban bao bba bbb bbc bbm bbn bbo bca bcb bcc bcm bcn bco bma bmb bmc bmm bmn bmo bna bnb bnc bnn bno boa bob boc bom bon boo c-- caa cab cac cam can cao cba cbb cbc cbm cbn cbo cca ccb ccc ccm ccn cco cma cmb cmc cmm cmn cmo cn- cna cnb cnc cnm cnn cno co- coa cob coc com con coo m-o maa mab mac mam man mao mba mbb mbc mbm mbo mc- mca mcb mcc mcm mcn mco mma mmb mmc mmm mmn mmo mna mnb mnc mnm mnn mno moa mob moc mom mon moo naa nab nac nam nan nao nba nbb nbc nbm nbn nbo nca ncb ncc ncm ncn nco nma nmb nmc nmm nmn nmo nna nnb nnc nnm nnn nno no- noa nob noc nom non noo oaa oab oac oam oan oao ob- oba obb obc obm obn obo oc- oca ocb occ ocm ocn oco om- oma omb omc omm omn omo on- ona onb onc onn ono oo- ooa oob ooc oom oon ooo