-ol bbb bbc bbk bbl bbo bcb bcc bck bcl bco bcv bkb bkc bkk bkl bko bkv blb blc blk bll blo blv bob boc bok bol boo bov bvb bvc bvk bvl bvo bvv c-- cbb cbc cbk cbl cbo cbv ccb ccc cck ccl cco ccv ckb ckc cko cl- clb clc clk cll clo clv co- cob coc cok col coo cov cvb cvc cvk cvl cvo cvv kbb kbc kbk kbl kbo kcb kcc kck kcl kkb kkc kkk kkl kkv kl- klb klc klo klv kob koc kok kol koo kvb kvk kvo kvv lbb lbc lbk lbl lbo lbv lcb lcc lck lcl lco lcv lkb lkl llb llc llk lll llo llv lob loc lok lol loo lov lvb lvc lvl lvv ob- obb obc obk obl obo obv oc- ocb occ ock ocl oco ocv okb okc okk okl oko olb olc olk oll olo oo- oob ooc ook ool ooo oov ov- ovb ovc ovl ovo ovv vbc vbk vbl vbo vbv vcc vcl vco vkb vl- vlb vlc vlk vll vlo vlv vob voc vok vol voo vov vvb vvc vvo vvv