bbb bbi bbl bbr bbs bbt bi- bib bii bil bir bis bit blb bli bll blr bls blt brb bri brl brr brs brt bsb bsi bsl bsr bss bst btb bti btl btr bts btt ibb ibi ibl ibr ibs ibt iib iii iil iir iis iit il- ilb ili ill ilr ils ilt ir- irb iri irl irr irs irt is- isb isi isl isr iss ist itb iti itl its itt lbb lbi lbl lbr lbs lbt lib lii lil lir lis lit llb lli lll llr lls llt lrb lri lrr lrs lrt lsb lsi lsl lsr lss lst ltb lti ltl ltr lts ltt rbb rbi rbl rbr rbs rbt rib rii ril rir ris rit rli rll rlr rls rlt rrb rri rrl rrr rrs rrt rsb rsi rsl rsr rss rst rtb rti rtl rtr rts rtt sbb sbi sbl sbr sbs sbt sib sii sil sir sis sit slb sli sll slr sls slt sr- srb sri srl srr srs srt ss- ssb ssi ssl ssr sss sst stb sti stl str sts stt tbb tbi tbl tbr tbs tbt tib tii til tir tis tit tli tll tlr tls tlt trb tri trl trr trs trt tsb tsi tsl tsr tss tst ttb tti ttl ttr tts ttt