bbb bbm bbo bbr bbs bmb bmm bmo bmr bms bob bom boo bor bos brb brm bro brr brs bsb bsm bso bsr bss m-o m-r mbb mbm mbo mbr mbs mmb mmm mmo mmr mms mob mom moo mor mos mrb mrm mro mrr mrs msb msm mso msr mss ob- obb obm obo obr obs om- omb omm omo omr oms oo- oob oom ooo oor oos or- orb orm oro orr ors os- osb osm oso osr oss rbb rbm rbo rbr rbs rmb rmm rmo rmr rms rob rom roo ror ros rrb rrm rrr rrs rsb rsm rso rsr rss sbb sbm sbo sbr sbs smb smm smo smr sms sob som soo sor sos sr- srb srm sro srr srs ss- ssb ssm sso ssr sss