bbb bbc bbo bbr bbs bby bcb bcc bco bcr bcs bcy bob boc boo bor bos boy brb bro brr brs bry bsb bsc bso bsr bss bsy by- byc byo byr bys c-- cbb cbc cbo cbr cbs cby ccb ccc cco ccr ccs co- cob coc coo cor cos coy crb crc cro crr crs cry csb csc cso csr css csy cyb cyc cyo cyr cys ob- obb obc obo obr obs oby oc- ocb occ oco ocr ocs oo- oob ooc ooo oor oos or- orb orc oro orr ors ory os- osb osc oso osr oss oyo oys rbb rbc rbo rbr rbs rcb rcc rco rcr rcs rob roc roo ror ros roy rrb rrc rrr rrs rsb rsc rso rsr rss ry- ryc ryo ryr rys ryy sbb sbc sbo sbr sbs sby scb scc sco scr scs sob soc soo sor sos soy sr- srb src sro srr srs sry ss- ssb ssc sso ssr sss sy- syb syc syr sys ybc ybr ybs yby ycc yco ycs ycy yob yoc yoo yor yos yoy yrc yro yrs ysb ysc yso ysr yss ysy yyb yyc yys yyy