-er bbb bbe bbk bbl bbr bbs be- beb bee bek bel ber bes bkb bke bkk bkl bkr bks blb ble blk bll blr bls brb bre brk brl brr brs bsb bse bsk bsl bsr bss ebb ebe ebk ebl ebr ebs eeb eee eek eel eer ees ekb eke ekl ekr eks elb ele elk ell elr els erb ere erk erl err ers es- esb ese esk esl esr ess kbb kbe kbk kbl kbr kbs ke- keb kee kek kel ker kes kkb kke kkk kkl kkr kks kl- klb klr kls krk krl krr krs ksb kse ksk ksl ksr kss lbb lbe lbk lbl lbr lbs leb lee lek lel ler les lkb lkl lkr lks llb lle llk lll llr lls lrb lrk lrr lrs lsb lse lsk lsl lsr lss rbb rbe rbk rbl rbr rbs re- reb ree rek rel rer res rkb rke rkk rks rle rll rlr rls rrb rrk rrl rrr rrs rsb rse rsk rsl rsr rss sbb sbe sbk sbl sbr sbs se- seb see sek sel ser ses sk- skb ske skk skl skr sks slb sle slk sll slr sls sr- srb sre srk srl srr srs ss- ssb sse ssk ssl ssr sss