-er bbb bbe bbi bbl bbr bbs bbt bbx be- beb bee bei bel ber bes bet bex bi- bib bie bii bil bir bis bit bix blb ble bli bll blr bls blt blx brb bre bri brl brr brs brt brx bsb bse bsi bsl bsr bss bst bsx btb bte bti btl btr bts btt btx bxb bxi bxl bxx ebb ebe ebi ebl ebr ebs ebt ebx eeb eee eel eer ees eet eex eib eie eii eil eir eis eit eix elb ele eli ell elr els elt elx erb ere eri erl err ers ert es- esb ese esi esl esr ess est esx etb ete eti etl etr ets ett etx ex- exe exi exl exr exs ext exx ibb ibe ibi ibl ibr ibs ibt ibx ie- iee iei iel ier ies iet iex iib iie iii iil iir iis iit iix il- ilb ile ili ill ilr ils ilt ilx ir- irb ire iri irl irr irs irt irx is- isb ise isi isl isr iss ist itb ite iti itl its itt itx ixe ixi ixl lbb lbe lbi lbl lbr lbs lbt lbx leb lee lei lel ler les let lex lib lie lii lil lir lis lit lix llb lle lli lll llr lls llt lrb lri lrr lrs lrt lsb lse lsi lsl lsr lss lst ltb lte lti ltl ltr lts ltt ltx lxi lxr lxx rbb rbe rbi rbl rbr rbs rbt rbx re- reb ree rei rel rer res ret rex rib rie rii ril rir ris rit rix rle rli rll rlr rls rlt rrb rri rrl rrr rrs rrt rsb rse rsi rsl rsr rss rst rsx rtb rte rti rtl rtr rts rtt rtx rxr rxs sbb sbe sbi sbl sbr sbs sbt sbx se- seb see sei sel ser ses set sex sib sie sii sil sir sis sit six slb sle sli sll slr sls slt slx sr- srb sre sri srl srr srs srt srx ss- ssb sse ssi ssl ssr sss sst ssx stb ste sti stl str sts stt stx sxi sxl sxs sxt t-x tbb tbe tbi tbl tbr tbs tbt te- teb tee tei tel ter tes tet tex tib tie tii til tir tis tit tix tle tli tll tlr tls tlt tlx trb tre tri trl trr trs trt trx tsb tse tsi tsl tsr tss tst tsx ttb tte tti ttl ttr tts ttt ttx txe txi txl txs txt xbe xbl xbr xbx xee xel xer xes xet xex xie xii xis xit xix xlb xli xlr xls xlt xrt xrx xsb xsi xsl xss xst xti xtr xts xtx xxi xxl xxx