bbb bbm bbo bbr bbs bbt bmb bmm bmo bmr bms bmt bob bom boo bor bos bot brb brm bro brr brs brt bsb bsm bso bsr bss bst btb btm bto btr bts btt m-o m-r mbb mbm mbo mbr mbs mbt mmb mmm mmo mmr mms mmt mob mom moo mor mos mot mrb mrm mro mrr mrs mrt msb msm mso msr mss mst mtb mtm mto mtr mts mtt ob- obb obm obo obr obs obt om- omb omm omo omr oms omt oo- oob oom ooo oor oos oot or- orb orm oro orr ors ort os- osb osm oso osr oss ost ot- otb otm oto otr ots ott rbb rbm rbo rbr rbs rbt rmb rmm rmo rmr rms rmt rob rom roo ror ros rot rrb rrm rrr rrs rrt rsb rsm rso rsr rss rst rtb rtm rto rtr rts rtt sbb sbm sbo sbr sbs sbt smb smm smo smr sms smt sob som soo sor sos sot sr- srb srm sro srr srs srt ss- ssb ssm sso ssr sss sst stb stm sto str sts stt tbb tbm tbo tbr tbs tbt tmb tmm tmo tmr tms tmt to- tob tom too tor tos tot trb trm tro trr trs trt tsb tsm tso tsr tss tst ttb ttm tto ttr tts ttt