b-u bbb bbi bbn bbr bbu bi- bib bii bin bir biu bnb bni bnn bnr bnu brb bri brn brr bru bub bui bun bur buu ibb ibi ibn ibr ibu iib iii iin iir iiu in- inb ini inn inr inu ir- irb iri irn irr iru iu- iub iui iur n-i nbb nbi nbn nbr nbu nib nii nin nir niu nnb nni nnn nnu nrb nri nrn nrr nru nub nui nun nur nuu rbb rbi rbn rbr rbu rib rii rin rir rnb rni rnn rnr rnu rrb rri rrn rrr rru rub rui run rur ruu ubb ubi ubn ubr ubu uib uii uin uir uiu un- unb uni unn unr unu ur- urb uri urn urr uru uun uur uuu