bbb bbn bbo bbr bnb bnn bno bnr bnz bob bon boo bor boz brb brn bro brr brz bzn bzo bzr bzz nbb nbn nbo nbr nnb nnn nno nnz no- nob non noo nor noz nrb nrn nro nrr nrz nzb nzo nzz ob- obb obn obo obr on- onb onn ono onr oo- oob oon ooo oor or- orb orn oro orr orz ozo ozz rbb rbn rbo rbr rnb rnn rno rnr rnz rob ron roo ror roz rrb rrn rrr rzb rzo zbb zbr znn zno zo- zob zon zoo zor zro zzr zzz