-er eee eef eep eer ees eet ef- efe eff efp efr efs eft ep- epe epf epp epr eps ept ere erf erp err ers ert es- ese esf esp esr ess est ete etf etp etr ets ett fee fef fep fer fes fet ffe fff ffp ffr ffs fft fpe fpp fpr fps fpt fre frf frp frr frs frt fse fsf fsp fsr fss fst fte ftf ftp ftr fts ftt p-p pee pef pep per pes pet pfe pff pfp pfr pfs pft ppe ppf ppp ppr pps ppt pre prf prp prr prs prt ps- pse psf psp psr pss pst pt- pte ptf ptp ptr pts ptt re- ree ref rep rer res ret rfe rff rfp rfr rfs rft rpe rpf rpp rpr rps rpt rrf rrp rrr rrs rrt rse rsf rsp rsr rss rst rte rtf rtp rtr rts rtt se- see sef sep ser ses set sfe sff sfp sfr sfs sft spe spf spp spr sps spt sr- sre srf srp srr srs srt ss- sse ssf ssp ssr sss sst ste stf stp str sts stt te- tee tef tep ter tes tet tfe tff tfp tfr tfs tft tpe tpf tpp tpr tps tpt tre trf trp trr trs trt tse tsf tsp tsr tss tst tte ttf ttp ttr tts ttt