bbb bbg bbo bbr bbs bbt bgb bgg bgo bgr bgs bgt bob bog boo bor bos bot brb brg bro brr brs brt bsb bsg bso bsr bss bst btb btg bto btr bts btt gbg gbo gbr gbs gbt ggb ggg ggo ggr ggs ggt gob gog goo gor gos got grb grg gro grr grs grt gsb gsg gso gsr gss gst gtb gtg gto gtr gts gtt ob- obb obg obo obr obs obt ogg ogo ogs ogt oo- oob oog ooo oor oos oot or- orb org oro orr ors ort os- osb osg oso osr oss ost ot- otb otg oto otr ots ott rbb rbg rbo rbr rbs rbt rgb rgg rgo rgr rgs rgt rob rog roo ror ros rot rrb rrg rrr rrs rrt rsb rsg rso rsr rss rst rtb rtg rto rtr rts rtt sbb sbg sbo sbr sbs sbt sgb sgg sgo sgr sgs sgt sob sog soo sor sos sot sr- srb srg sro srr srs srt ss- ssb ssg sso ssr sss sst stb stg sto str sts stt tbb tbg tbo tbr tbs tbt tgb tgg tgo tgr tgs tgt to- tob tog too tor tos tot trb trg tro trr trs trt tsb tsg tso tsr tss tst ttb ttg tto ttr tts ttt