-er bbb bbe bbk bbn bbr bbs be- beb bee bek ben ber bes bkb bke bkk bkn bkr bks bnb bne bnk bnn bnr bns brb bre brk brn brr brs bsb bse bsk bsn bsr bss ebb ebe ebk ebn ebr ebs eeb eee eek een eer ees ekb eke ekr eks en- enb ene enk enn enr ens erb ere erk ern err ers es- esb ese esk esn esr ess kbb kbe kbk kbn kbr kbs ke- keb kee kek ken ker kes kkb kke kkk kkn kkr kks kn- kne knk knn knr krk krn krr krs ksb kse ksk ksn ksr kss nbb nbe nbk nbn nbr nbs ne- neb nee nek nen ner nes nke nkk nkn nkr nks nnb nne nnk nnn nns nrb nre nrk nrn nrr nrs nsb nse nsk nsn nsr nss rbb rbe rbk rbn rbr rbs re- reb ree rek ren rer res rkb rke rkk rks rnb rnn rnr rns rrb rrk rrn rrr rrs rsb rse rsk rsn rsr rss sbb sbe sbk sbn sbr sbs se- seb see sek sen ser ses sk- skb ske skk skr sks snb sne snk snn snr sns sr- srb sre srk srn srr srs ss- ssb sse ssk ssn ssr sss