bbb bbi bbn bbr bbs bi- bib bii bin bir bis bnb bni bnn bnr bns brb bri brn brr brs bsb bsi bsn bsr bss ibb ibi ibn ibr ibs iib iii iin iir iis in- inb ini inn inr ins ir- irb iri irn irr irs is- isb isi isn isr iss n-i nbb nbi nbn nbr nbs nib nii nin nir nis nnb nni nnn nns nrb nri nrn nrr nrs nsb nsi nsn nsr nss rbb rbi rbn rbr rbs rib rii rin rir ris rnb rni rnn rnr rns rrb rri rrn rrr rrs rsb rsi rsn rsr rss sbb sbi sbn sbr sbs sib sii sin sir sis snb sni snn snr sns sr- srb sri srn srr srs ss- ssb ssi ssn ssr sss