bbb bbk bbm bbo bbs bkb bkk bkm bko bks bmb bmk bmm bmo bms bob bok bom boo bos bsb bsk bsm bso bss kbb kbk kbm kbo kbs kkb kkk kkm kks kmb kmk kmm kmo kms kob kok kom koo kos ksb ksk ksm kso kss m-o mbb mbk mbm mbo mbs mkb mkk mkm mko mks mmb mmk mmm mmo mms mob mok mom moo mos msb msk msm mso mss ob- obb obk obm obo obs okb okk oko oks om- omb omm omo oms oo- oob ook oom ooo oos os- osb osk osm oso oss sbb sbk sbm sbo sbs sk- skb skk skm sko sks smb smk smm smo sms sob sok som soo sos ss- ssb ssk ssm sso sss