bbb bbi bbl bbr bbs bi- bib bii bil bir bis blb bli bll blr bls brb bri brl brr brs bsb bsi bsl bsr bss ibb ibi ibl ibr ibs iib iii iil iir iis il- ilb ili ill ilr ils ir- irb iri irl irr irs is- isb isi isl isr iss lbb lbi lbl lbr lbs lib lii lil lir lis llb lli lll llr lls lrb lri lrr lrs lsb lsi lsl lsr lss rbb rbi rbl rbr rbs rib rii ril rir ris rli rll rlr rls rrb rri rrl rrr rrs rsb rsi rsl rsr rss sbb sbi sbl sbr sbs sib sii sil sir sis slb sli sll slr sls sr- srb sri srl srr srs ss- ssb ssi ssl ssr sss