a-a a-b a-i aaa aab aai aan aar aax ab- aba abb abi abn abr abx ai- aia aib aii ain air aix an- ana anb ani ann anr anx ar- ara arb ari arn arr arx ax- axa axi axn axr axx baa bab bai ban bar bax bba bbb bbi bbn bbr bbx bi- bia bib bii bin bir bix bna bnb bni bnn bnr bnx bra brb bri brn brr brx bxb bxi bxn bxx ia- iaa iab iai ian iar iba ibb ibi ibn ibr ibx iia iib iii iin iir iix in- ina inb ini inn inr inx ir- ira irb iri irn irr irx ixi ixn n-i naa nab nai nan nar nax nba nbb nbi nbn nbr nbx nia nib nii nin nir nix nna nnb nni nnn nra nrb nri nrn nrr nrx ra- raa rab rai ran rar rax rba rbb rbi rbn rbr rbx ria rib rii rin rir rix rna rnb rni rnn rnr rra rrb rri rrn rrr rxr xaa xan xar xbr xbx xia xii xin xix xna xrx xxi xxx