-er eee eef eek eep eer ees ef- efe eff efi efp efr efs eie eif eii eik eip eir eis eke ekf eki ekp ekr eks ep- epe epf epi epp epr eps ere erf eri erk erp err ers es- ese esf esi esk esp esr ess fee fef fei fek fep fer fes ffe fff ffi ffk ffp ffr ffs fie fif fii fik fip fir fis fkf fki fkk fkp fpe fpi fpk fpp fpr fps fre frf fri frk frp frr frs fse fsf fsi fsk fsp fsr fss i-f ie- iee ief iei iek iep ier ies ife iff ifi ifp ifr ifs iie iif iii iip iir iis ike ikf iki ikk ikr iks ipe ipf ipi ipp ipr ips ir- ire irf iri irk irp irr irs is- ise isf isi isk isp isr iss ke- kee kef kei kek kep ker kes kff kfi kfs kie kif kii kik kip kir kis kke kki kkk kkp kkr kks kpe kpf kpi kpk kpp kpr kps krf kri krk krp krr krs kse ksf ksi ksk ksp ksr kss p-p pee pef pei pek pep per pes pfe pff pfi pfk pfp pfr pfs pie pif pii pik pip pir pis pke pkf pki pkp pkr pks ppe ppf ppi ppk ppp ppr pps pre prf pri prk prp prr prs ps- pse psf psi psk psp psr pss re- ree ref rei rek rep rer res rfe rff rfi rfk rfp rfr rfs rie rif rii rik rip rir ris rke rkf rkk rkp rks rpe rpf rpi rpk rpp rpr rps rrf rri rrk rrp rrr rrs rse rsf rsi rsk rsp rsr rss se- see sef sei sek sep ser ses sfe sff sfi sfk sfp sfr sfs sie sif sii sik sip sir sis sk- ske skf ski skk skp skr sks spe spf spi spk spp spr sps sr- sre srf sri srk srp srr srs ss- sse ssf ssi ssk ssp ssr sss