bbb bbd bbo bbr bbs bbt bdb bdd bdo bdr bds bdt bob bod boo bor bos bot brb brd bro brr brs brt bsb bsd bso bsr bss bst btb btd bto btr bts btt dbb dbd dbo dbr dbs dbt ddb ddd ddo ddr dds ddt dob dod doo dor dos dot drb drd dro drr drs drt dsb dsd dso dsr dss dst dtb dtd dto dtr dts dtt ob- obb obd obo obr obs obt odb odd odo odr ods odt oo- oob ood ooo oor oos oot or- orb ord oro orr ors ort os- osb osd oso osr oss ost ot- otb otd oto otr ots ott rbb rbd rbo rbr rbs rbt rdb rdd rdo rdr rds rdt rob rod roo ror ros rot rrb rrd rrr rrs rrt rsb rsd rso rsr rss rst rtb rtd rto rtr rts rtt sbb sbd sbo sbr sbs sbt sdb sdd sdo sdr sds sdt sob sod soo sor sos sot sr- srb srd sro srr srs srt ss- ssb ssd sso ssr sss sst stb std sto str sts stt tbb tbd tbo tbr tbs tbt tdb tdd tdo tdr tds tdt to- tob tod too tor tos tot trb trd tro trr trs trt tsb tsd tso tsr tss tst ttb ttd tto ttr tts ttt