a-a a-c aaa aac aad aan aao aax ac- aca acc acd acn aco acx ad- ada adc add adn ado adx an- ana anc and ann ano anx aoa aoc aod aon aoo aox ax- axa axn axo axx c-- caa cac cad can cao cax cca ccc ccd ccn cco ccx cda cdc cdd cdn cdo cdx cn- cna cnc cnd cnn cno cnx co- coa coc cod con coo cox cxc cxo cxx daa dac dad dan dao dax dca dcc dcd dcn dco dcx dda ddc ddd ddn ddo ddx dna dnc dnd dnn dno doa doc dod don doo dox dxc dxd dxn dxo dxx naa nac nad nan nao nax nca ncc ncd ncn nco ncx nda ndc ndd ndn ndo nna nnc nnn nno no- noa noc nod non noo nox nxc nxd oaa oac oad oan oao oax oc- oca occ ocd ocn oco ocx oda odc odd odn odo on- ona onc ond onn ono onx oo- ooa ooc ood oon ooo oox ox- oxa oxc oxn oxo oxx xaa xac xad xan xcd xcx xda xdc xna xnc xno xoa xoc xod xon xoo xox xxo xxx