-er eee eef eeo eer ees ef- efe eff efo efr efs eo- eoe eof eoo eor eos ere erf ero err ers es- ese esf eso esr ess fee fef feo fer fes ffe fff ffo ffr ffs foe fof foo for fos fre frf fro frr frs fse fsf fso fsr fss oee oef oeo oer oes of- ofe off ofo ofr ofs oo- oof ooo oor oos or- ore orf oro orr ors os- ose osf oso osr oss re- ree ref reo rer res rfe rff rfo rfr rfs roe rof roo ror ros rrf rrr rrs rse rsf rso rsr rss se- see sef seo ser ses sfe sff sfo sfr sfs soe sof soo sor sos sr- sre srf sro srr srs ss- sse ssf sso ssr sss