bbb bbh bbk bbo bbs bhb bhh bhk bho bhs bkb bkk bko bks bob boh bok boo bos bsb bsh bsk bso bss hbb hbh hbk hbo hbs hhb hhh hhk hho hhs hkb hkh hkk hko hks hob hoh hok hoo hos hsb hsh hsk hss kbb kbh kbk kbo kbs khh khk kho khs kkb kkh kkk kks kob koh kok koo kos ksb ksh ksk kso kss ob- obb obh obk obo obs ohh oho ohs okb okk oko oks oo- oob ooh ook ooo oos os- osb osh osk oso oss sbb sbh sbk sbo sbs sh- shb shh shk sho shs sk- skb skh skk sko sks sob soh sok soo sos ss- ssb ssh ssk sso sss