-ol bbb bbc bbk bbl bbo bbr bbs bcb bcc bck bcl bco bcr bcs bkb bkc bkk bkl bko bkr bks blb blc blk bll blo blr bls bob boc bok bol boo bor bos brb brk brl bro brr brs bsb bsc bsk bsl bso bsr bss c-- cbb cbc cbk cbl cbo cbr cbs ccb ccc cck ccl cco ccr ccs ckb ckc cko cks cl- clb clc clk cll clo clr cls co- cob coc cok col coo cor cos crb crc crk crl cro crr crs csb csc csk csl cso csr css kbb kbc kbk kbl kbo kbr kbs kcb kcc kck kcl kcr kcs kkb kkc kkk kkl kkr kks kl- klb klc klo klr kls kob koc kok kol koo kor kos krc krk krl kro krr krs ksb ksc ksk ksl kso ksr kss lbb lbc lbk lbl lbo lbr lbs lcb lcc lck lcl lco lcr lcs lkb lkl lkr lks llb llc llk lll llo llr lls lob loc lok lol loo lor los lrb lrc lrk lro lrr lrs lsb lsc lsk lsl lso lsr lss ob- obb obc obk obl obo obr obs oc- ocb occ ock ocl oco ocr ocs okb okc okk okl oko okr oks olb olc olk oll olo ols oo- oob ooc ook ool ooo oor oos or- orb orc ork orl oro orr ors os- osb osc osk osl oso osr oss rbb rbc rbk rbl rbo rbr rbs rcb rcc rcl rco rcr rcs rkb rkc rkk rko rks rlc rll rlo rlr rls rob roc rok rol roo ror ros rrb rrc rrk rrl rrr rrs rsb rsc rsk rsl rso rsr rss sbb sbc sbk sbl sbo sbr sbs scb scc sck scl sco scr scs sk- skb skc skk skl sko skr sks slb slc slk sll slo slr sls sob soc sok sol soo sor sos sr- srb src srk srl sro srr srs ss- ssb ssc ssk ssl sso ssr sss