-ol bbb bbi bbl bbo bbr bbs bbt bi- bib bii bil bio bir bis bit blb bli bll blo blr bls blt bob boi bol boo bor bos bot brb bri brl bro brr brs brt bsb bsi bsl bso bsr bss bst btb bti btl bto btr bts btt ibb ibi ibl ibo ibr ibs ibt iib iii iil iio iir iis iit il- ilb ili ill ilo ilr ils ilt io- iob ioi iol ioo ior ios iot ir- irb iri irl iro irr irs irt is- isb isi isl iso isr iss ist itb iti itl ito its itt lbb lbi lbl lbo lbr lbs lbt lib lii lil lio lir lis lit llb lli lll llo llr lls llt lob loi lol loo lor los lot lrb lri lro lrr lrs lrt lsb lsi lsl lso lsr lss lst ltb lti ltl lto ltr lts ltt o-i ob- obb obi obl obo obr obs obt oib oii oil oio oir ois oit olb oli oll olo ols olt oo- oob ooi ool ooo oor oos oot or- orb ori orl oro orr ors ort os- osb osi osl oso osr oss ost ot- otb oti otl oto otr ots ott rbb rbi rbl rbo rbr rbs rbt rib rii ril rio rir ris rit rli rll rlo rlr rls rlt rob roi rol roo ror ros rot rrb rri rrl rrr rrs rrt rsb rsi rsl rso rsr rss rst rtb rti rtl rto rtr rts rtt sbb sbi sbl sbo sbr sbs sbt sib sii sil sio sir sis sit slb sli sll slo slr sls slt sob soi sol soo sor sos sot sr- srb sri srl sro srr srs srt ss- ssb ssi ssl sso ssr sss sst stb sti stl sto str sts stt tbb tbi tbl tbo tbr tbs tbt tib tii til tio tir tis tit tli tll tlo tlr tls tlt to- tob toi tol too tor tos tot trb tri trl tro trr trs trt tsb tsi tsl tso tsr tss tst ttb tti ttl tto ttr tts ttt