bbb bbm bbo bbr bmb bmm bmo bmr bmz bob bom boo bor boz brb brm bro brr brz bzo bzr bzz m-o m-r mbb mbm mbo mbr mmb mmm mmo mmr mmz mob mom moo mor moz mrb mrm mro mrr mrz mzb mzm ob- obb obm obo obr om- omb omm omo omr omz oo- oob oom ooo oor or- orb orm oro orr orz ozm ozo ozz rbb rbm rbo rbr rmb rmm rmo rmr rob rom roo ror roz rrb rrm rrr rzb rzm rzo zbb zbm zbr zmb zmm zo- zob zom zoo zor zro zzr zzz