-er eee eer ees eet eex ere err ers ert eru es- ese esr ess est esu esx ete etr ets ett etu etx eu- eue eur eus eut eux ex- exe exr exs ext exu exx re- ree rer res ret reu rex rrr rrs rrt rru rse rsr rss rst rsu rsx rte rtr rts rtt rtu rtx rue rur rus rut ruu rux rxr rxs se- see ser ses set seu sex sr- sre srr srs srt srx ss- sse ssr sss sst ssu ssx ste str sts stt stu stx sue sur sus sut suu sux sxs sxt sxu t-x te- tee ter tes tet teu tex tre trr trs trt tru trx tse tsr tss tst tsu tsx tte ttr tts ttt ttu ttx tue tur tus tut tuu tux txe txs txt txu uee uer ues uet ur- ure urr urs urt uru urx use usr uss ust usu usx ute utr uts utt utu utx uue uur uus uut uuu uxr uxt uxu xee xer xes xet xeu xex xrt xrx xss xst xtr xts xtx xue xus xxx