a-a a-b a-i aaa aab aai aan aao ab- aba abb abi abn abo ai- aia aib aii ain aio an- ana anb ani ann ano aoa aob aoi aon aoo baa bab bai ban bao bba bbb bbi bbn bbo bi- bia bib bii bin bio bna bnb bni bnn bno boa bob boi bon boo ia- iaa iab iai ian iao iba ibb ibi ibn ibo iia iib iii iin iio in- ina inb ini inn ino io- ioa iob ioi ion ioo n-i naa nab nai nan nao nba nbb nbi nbn nbo nia nib nii nin nio nna nnb nni nnn nno no- noa nob noi non noo o-i oaa oab oai oan oao ob- oba obb obi obn obo oia oib oii oin oio on- ona onb oni onn ono oo- ooa oob ooi oon ooo