a-a a-b a-i aaa aab aai aan aao aar aax ab- aba abb abi abn abo abr abx ai- aia aib aii ain aio air aix an- ana anb ani ann ano anr anx aoa aob aoi aon aoo aor aox ar- ara arb ari arn aro arr arx ax- axa axi axn axo axr axx baa bab bai ban bao bar bax bba bbb bbi bbn bbo bbr bbx bi- bia bib bii bin bio bir bix bna bnb bni bnn bno bnr bnx boa bob boi bon boo bor box bra brb bri brn bro brr brx bxb bxi bxn bxo bxx ia- iaa iab iai ian iao iar iba ibb ibi ibn ibo ibr ibx iia iib iii iin iio iir iix in- ina inb ini inn ino inr inx io- ioa iob ioi ion ioo ior ir- ira irb iri irn iro irr irx ixi ixn n-i naa nab nai nan nao nar nax nba nbb nbi nbn nbo nbr nbx nia nib nii nin nio nir nix nna nnb nni nnn nno no- noa nob noi non noo nor nox nra nrb nri nrn nro nrr nrx o-i oaa oab oai oan oao oar oax ob- oba obb obi obn obo obr obx oia oib oii oin oio oir on- ona onb oni onn ono onr onx oo- ooa oob ooi oon ooo oor oox or- ora orb ori orn oro orr orx ox- oxa oxb oxi oxn oxo oxx ra- raa rab rai ran rao rar rax rba rbb rbi rbn rbo rbr rbx ria rib rii rin rio rir rix rna rnb rni rnn rno rnr roa rob roi ron roo ror rox rra rrb rri rrn rrr rxr xaa xan xar xbr xbx xia xii xin xio xix xna xno xoa xoi xon xoo xor xox xrx xxi xxo xxx