bbb bbd bbk bbo bbs bdb bdd bdk bdo bds bkb bkk bko bks bob bod bok boo bos bsb bsd bsk bso bss dbb dbd dbk dbo dbs ddb ddd ddk ddo dds dkb dkk dko dks dob dod dok doo dos dsb dsd dsk dso dss kbb kbd kbk kbo kbs kdb kdk kdo kds kkb kkk kks kob kod kok koo kos ksb ksd ksk kso kss ob- obb obd obk obo obs odb odd odo ods okb okd okk oko oks oo- oob ood ook ooo oos os- osb osd osk oso oss sbb sbd sbk sbo sbs sdb sdd sdk sdo sds sk- skb skd skk sko sks sob sod sok soo sos ss- ssb ssd ssk sso sss