-er eee eef eek een eer ees ef- efe eff efr efs eke ekf ekr eks en- ene enf enk enn enr ens ere erf erk ern err ers es- ese esf esk esn esr ess fee fef fek fen fer fes ffe fff ffk ffn ffr ffs fkf fkk fne fnf fnk fnn fnr fns fre frf frk frn frr frs fse fsf fsk fsn fsr fss ke- kee kef kek ken ker kes kff kfs kke kkk kkn kkr kks kn- kne knf knk knn knr krf krk krn krr krs kse ksf ksk ksn ksr kss ne- nee nef nek nen ner nes nfe nff nfk nfn nfr nfs nke nkf nkk nkn nkr nks nne nnf nnk nnn nns nre nrf nrk nrn nrr nrs nse nsf nsk nsn nsr nss re- ree ref rek ren rer res rfe rff rfk rfn rfr rfs rke rkf rkk rks rnn rnr rns rrf rrk rrn rrr rrs rse rsf rsk rsn rsr rss se- see sef sek sen ser ses sfe sff sfk sfn sfr sfs sk- ske skf skk skr sks sne snf snk snn snr sns sr- sre srf srk srn srr srs ss- sse ssf ssk ssn ssr sss