b-u bbb bbi bbn bbr bbs bbu bi- bib bii bin bir bis biu bnb bni bnn bnr bns bnu brb bri brn brr brs bru bsb bsi bsn bsr bss bsu bub bui bun bur bus buu ibb ibi ibn ibr ibs ibu iib iii iin iir iis iiu in- inb ini inn inr ins inu ir- irb iri irn irr irs iru is- isb isi isn isr iss isu iu- iub iui iur ius n-i nbb nbi nbn nbr nbs nbu nib nii nin nir nis niu nnb nni nnn nns nnu nrb nri nrn nrr nrs nru nsb nsi nsn nsr nss nsu nub nui nun nur nus nuu rbb rbi rbn rbr rbs rbu rib rii rin rir ris rnb rni rnn rnr rns rnu rrb rri rrn rrr rrs rru rsb rsi rsn rsr rss rsu rub rui run rur rus ruu sbb sbi sbn sbr sbs sbu sib sii sin sir sis siu snb sni snn snr sns snu sr- srb sri srn srr srs ss- ssb ssi ssn ssr sss ssu sub sui sun sur sus suu ubb ubi ubn ubr ubs ubu uib uii uin uir uis uiu un- unb uni unn unr uns unu ur- urb uri urn urr urs uru usb usi usn usr uss usu uun uur uus uuu