bbb bbc bbd bbo bbr bbs bcb bcc bcd bco bcr bcs bdb bdc bdd bdo bdr bds bob boc bod boo bor bos brb brd bro brr brs bsb bsc bsd bso bsr bss c-- cbb cbc cbd cbo cbr cbs ccb ccc ccd cco ccr ccs cdb cdc cdd cdo cdr cds co- cob coc cod coo cor cos crb crc crd cro crr crs csb csc csd cso csr css dbb dbc dbd dbo dbr dbs dcb dcc dcd dco dcr dcs ddb ddc ddd ddo ddr dds dob doc dod doo dor dos drb drc drd dro drr drs dsb dsc dsd dso dsr dss ob- obb obc obd obo obr obs oc- ocb occ ocd oco ocr ocs odb odc odd odo odr ods oo- oob ooc ood ooo oor oos or- orb orc ord oro orr ors os- osb osc osd oso osr oss rbb rbc rbd rbo rbr rbs rcb rcc rcd rco rcr rcs rdb rdc rdd rdo rdr rds rob roc rod roo ror ros rrb rrc rrd rrr rrs rsb rsc rsd rso rsr rss sbb sbc sbd sbo sbr sbs scb scc scd sco scr scs sdb sdc sdd sdo sdr sds sob soc sod soo sor sos sr- srb src srd sro srr srs ss- ssb ssc ssd sso ssr sss