bbb bbd bbo bbs bbt bdb bdd bdo bds bdt bob bod boo bos bot bsb bsd bso bss bst btb btd bto bts btt dbb dbd dbo dbs dbt ddb ddd ddo dds ddt dob dod doo dos dot dsb dsd dso dss dst dtb dtd dto dts dtt ob- obb obd obo obs obt odb odd odo ods odt oo- oob ood ooo oos oot os- osb osd oso oss ost ot- otb otd oto ots ott sbb sbd sbo sbs sbt sdb sdd sdo sds sdt sob sod soo sos sot ss- ssb ssd sso sss sst stb std sto sts stt tbb tbd tbo tbs tbt tdb tdd tdo tds tdt to- tob tod too tos tot tsb tsd tso tss tst ttb ttd tto tts ttt