-ol bbb bbc bbl bbo bbs bbt bcb bcc bcl bco bcs bct blb blc bll blo bls blt bob boc bol boo bos bot bsb bsc bsl bso bss bst btb btc btl bto bts btt c-- cbb cbc cbl cbo cbs cbt ccb ccc ccl cco ccs cct cl- clb clc cll clo cls clt co- cob coc col coo cos cot csb csc csl cso css cst ctb ctc ctl cto cts ctt lbb lbc lbl lbo lbs lbt lcb lcc lcl lco lcs lct llb llc lll llo lls llt lob loc lol loo los lot lsb lsc lsl lso lss lst ltb ltc ltl lto lts ltt ob- obb obc obl obo obs obt oc- ocb occ ocl oco ocs oct olb olc oll olo ols olt oo- oob ooc ool ooo oos oot os- osb osc osl oso oss ost ot- otb otc otl oto ots ott sbb sbc sbl sbo sbs sbt scb scc scl sco scs sct slb slc sll slo sls slt sob soc sol soo sos sot ss- ssb ssc ssl sso sss sst stb stc stl sto sts stt tbb tbc tbl tbo tbs tbt tcb tcc tcl tco tcs tct tlc tll tlo tls tlt to- tob toc tol too tos tot tsb tsc tsl tso tss tst ttb ttc ttl tto tts ttt