a-a a-b a-i aaa aab aai aan aao aax ab- aba abb abi abn abo abx ai- aia aib aii ain aio aix an- ana anb ani ann ano anx aoa aob aoi aon aoo aox ax- axa axi axn axo axx baa bab bai ban bao bax bba bbb bbi bbn bbo bbx bi- bia bib bii bin bio bix bna bnb bni bnn bno bnx boa bob boi bon boo box bxb bxi bxn bxo bxx ia- iaa iab iai ian iao iba ibb ibi ibn ibo ibx iia iib iii iin iio iix in- ina inb ini inn ino inx io- ioa iob ioi ion ioo ixi ixn n-i naa nab nai nan nao nax nba nbb nbi nbn nbo nbx nia nib nii nin nio nix nna nnb nni nnn nno no- noa nob noi non noo nox o-i oaa oab oai oan oao oax ob- oba obb obi obn obo obx oia oib oii oin oio on- ona onb oni onn ono onx oo- ooa oob ooi oon ooo oox ox- oxa oxb oxi oxn oxo oxx xaa xan xbx xia xii xin xio xix xna xno xoa xoi xon xoo xox xxi xxo xxx