a-a a-b aaa aab aad aan aao aax ab- aba abb abd abn abo abx ad- ada adb add adn ado adx an- ana anb and ann ano anx aoa aob aod aon aoo aox ax- axa axn axo axx baa bab bad ban bao bax bba bbb bbd bbn bbo bbx bda bdb bdd bdo bdx bna bnb bnd bnn bno bnx boa bob bod bon boo box bxb bxd bxn bxo bxx daa dab dad dan dao dax dba dbb dbd dbn dbo dbx dda ddb ddd ddn ddo ddx dna dnb dnd dnn dno doa dob dod don doo dox dxd dxn dxo dxx naa nab nad nan nao nax nba nbb nbd nbn nbo nbx nda ndb ndd ndn ndo nna nnb nnn nno no- noa nob nod non noo nox nxd oaa oab oad oan oao oax ob- oba obb obd obn obo obx oda odb odd odn odo on- ona onb ond onn ono onx oo- ooa oob ood oon ooo oox ox- oxa oxb oxn oxo oxx xaa xad xan xbx xda xdb xna xno xoa xod xon xoo xox xxo xxx