-er eee eek eep eer ees eie eii eik eip eir eis eke eki ekp ekr eks ep- epe epi epp epr eps ere eri erk erp err ers es- ese esi esk esp esr ess ie- iee iei iek iep ier ies iie iii iip iir iis ike iki ikk ikr iks ipe ipi ipp ipr ips ir- ire iri irk irp irr irs is- ise isi isk isp isr iss ke- kee kei kek kep ker kes kie kii kik kip kir kis kke kki kkk kkp kkr kks kpe kpi kpk kpp kpr kps kri krk krp krr krs kse ksi ksk ksp ksr kss p-p pee pei pek pep per pes pie pii pik pip pir pis pke pki pkp pkr pks ppe ppi ppk ppp ppr pps pre pri prk prp prr prs ps- pse psi psk psp psr pss re- ree rei rek rep rer res rie rii rik rip rir ris rke rkk rkp rks rpe rpi rpk rpp rpr rps rri rrk rrp rrr rrs rse rsi rsk rsp rsr rss se- see sei sek sep ser ses sie sii sik sip sir sis sk- ske ski skk skp skr sks spe spi spk spp spr sps sr- sre sri srk srp srr srs ss- sse ssi ssk ssp ssr sss