a-a a-b a-i aaa aab aai aan aar ab- aba abb abi abn abr ai- aia aib aii ain air an- ana anb ani ann anr ar- ara arb ari arn arr baa bab bai ban bar bba bbb bbi bbn bbr bi- bia bib bii bin bir bna bnb bni bnn bnr bra brb bri brn brr ia- iaa iab iai ian iar iba ibb ibi ibn ibr iia iib iii iin iir in- ina inb ini inn inr ir- ira irb iri irn irr n-i naa nab nai nan nar nba nbb nbi nbn nbr nia nib nii nin nir nna nnb nni nnn nra nrb nri nrn nrr ra- raa rab rai ran rar rba rbb rbi rbn rbr ria rib rii rin rir rna rnb rni rnn rnr rra rrb rri rrn rrr