-ol bbb bbc bbd bbk bbl bbo bcb bcc bcd bck bcl bco bdb bdc bdd bdk bdl bdo bkb bkc bkk bkl bko blb blc bld blk bll blo bob boc bod bok bol boo c-- cbb cbc cbd cbk cbl cbo ccb ccc ccd cck ccl cco cdb cdc cdd cdk cdl cdo ckb ckc ckd cko cl- clb clc cld clk cll clo co- cob coc cod cok col coo dbb dbc dbd dbk dbl dbo dcb dcc dcd dck dcl dco ddb ddc ddd ddk ddl ddo dkb dkc dkk dkl dko dl- dlb dlc dld dlk dll dlo dob doc dod dok dol doo kbb kbc kbd kbk kbl kbo kcb kcc kcd kck kcl kdb kdc kdk kdl kdo kkb kkc kkk kkl kl- klb klc kld klo kob koc kod kok kol koo lbb lbc lbd lbk lbl lbo lcb lcc lcd lck lcl lco ldb ldc ldd ldk ldl ldo lkb lkl llb llc lld llk lll llo lob loc lod lok lol loo ob- obb obc obd obk obl obo oc- ocb occ ocd ock ocl oco odb odc odd odl odo okb okc okd okk okl oko olb olc old olk oll olo oo- oob ooc ood ook ool ooo