b-u bbb bbn bbo bbr bbu bnb bnn bno bnr bnu bnz bob bon boo bor bou boz brb brn bro brr bru brz bub bun buo bur buu buz bzn bzo bzr bzu bzz nbb nbn nbo nbr nbu nnb nnn nno nnu nnz no- nob non noo nor nou noz nrb nrn nro nrr nru nrz nub nun nuo nur nuu nzb nzo nzz ob- obb obn obo obr obu on- onb onn ono onr onu oo- oob oon ooo oor or- orb orn oro orr oru orz ou- oun ouo our ozo ozu ozz rbb rbn rbo rbr rbu rnb rnn rno rnr rnu rnz rob ron roo ror rou roz rrb rrn rrr rru rub run ruo rur ruu ruz rzb rzo ubb ubn ubo ubr ubu un- unb unn uno unr unu uob uon uoo uor ur- urb urn uro urr uru urz uun uur uuu uzb uzo uzu zbb zbr znn zno zo- zob zon zoo zor zou zro zub zun zur zuz zzr zzz