-ol bbb bbf bbl bbo bbs bbt bfb bff bfl bfo bfs bft blb blf bll blo bls blt bob bof bol boo bos bot bsb bsf bsl bso bss bst btb btf btl bto bts btt fbb fbf fbl fbo fbs fbt fff ffl ffo ffs fft flb flf fll flo fls flt fob fof fol foo fos fot fsb fsf fsl fso fss fst ftb ftf ftl fto fts ftt lbb lbf lbl lbo lbs lbt lfb lff lfl lfo lfs lft llb llf lll llo lls llt lob lof lol loo los lot lsb lsf lsl lso lss lst ltb ltf ltl lto lts ltt ob- obb obf obl obo obs obt of- ofb off ofl ofo ofs oft olb olf oll olo ols olt oo- oob oof ool ooo oos oot os- osb osf osl oso oss ost ot- otb otf otl oto ots ott sbb sbf sbl sbo sbs sbt sfb sff sfl sfo sfs sft slb slf sll slo sls slt sob sof sol soo sos sot ss- ssb ssf ssl sso sss sst stb stf stl sto sts stt tbb tbf tbl tbo tbs tbt tfb tff tfl tfo tfs tft tlf tll tlo tls tlt to- tob tof tol too tos tot tsb tsf tsl tso tss tst ttb ttf ttl tto tts ttt