a-a a-b a-i aaa aab aai aak aan aao ab- aba abb abi abk abn abo ai- aia aib aii aik ain aio aka akb aki akk akn ako an- ana anb ani ank ann ano aoa aob aoi aok aon aoo baa bab bai bak ban bao bba bbb bbi bbk bbn bbo bi- bia bib bii bik bin bio bka bkb bkk bkn bko bna bnb bni bnk bnn bno boa bob boi bok bon boo ia- iaa iab iai ian iao iba ibb ibi ibk ibn ibo iia iib iii iin iio ika ikb iki ikk iko in- ina inb ini ink inn ino io- ioa iob ioi ion ioo ka- kaa kab kai kak kan kao kba kbb kbi kbk kbn kbo kia kib kii kik kin kio kkb kki kkk kkn kn- kna kni knk knn kno koa kob koi kok kon koo n-i naa nab nai nak nan nao nba nbb nbi nbk nbn nbo nia nib nii nik nin nio nka nki nkk nkn nko nna nnb nni nnk nnn nno no- noa nob noi nok non noo o-i oaa oab oai oak oan oao ob- oba obb obi obk obn obo oia oib oii oik oin oio oka okb oki okk oko on- ona onb oni onk onn ono oo- ooa oob ooi ook oon ooo