bbb bbi bbl bbr bbs bbx bi- bib bii bil bir bis bix blb bli bll blr bls blx brb bri brl brr brs brx bsb bsi bsl bsr bss bsx bxb bxi bxl bxx ibb ibi ibl ibr ibs ibx iib iii iil iir iis iix il- ilb ili ill ilr ils ilx ir- irb iri irl irr irs irx is- isb isi isl isr iss ixi ixl lbb lbi lbl lbr lbs lbx lib lii lil lir lis lix llb lli lll llr lls lrb lri lrr lrs lsb lsi lsl lsr lss lxi lxr lxx rbb rbi rbl rbr rbs rbx rib rii ril rir ris rix rli rll rlr rls rrb rri rrl rrr rrs rsb rsi rsl rsr rss rsx rxr rxs sbb sbi sbl sbr sbs sbx sib sii sil sir sis six slb sli sll slr sls slx sr- srb sri srl srr srs srx ss- ssb ssi ssl ssr sss ssx sxi sxl sxs xbl xbr xbx xii xis xix xlb xli xlr xls xrx xsb xsi xsl xss xxi xxl xxx