-tree e-ten eeeee eener eenet eepee eeten efere efetf effer effet efnet efren eften efter enent enete enfer ennet enper enten enter entre epeen epene eptfe ereen erept erere ernen ernet erte erter etern etete etnre etree etten etter feere fener fenne feren feret ferr- ferre ferte feter fette freep freer freet frere frett ftrtt n-p-n neere nefen nefer neffe nefre nefte nente neper neppe nepte neree neret nerre nerte neten netne nette ntete p-n-p p-rep peene peent peere peert peete pene- pener penne penre pent- pente pepee peppe pept- peren perer peret perne pernt perre perte peter petr- petre pette pptnt preef preen preff prene prent prepn prete prntr pter- ptere ptpre ptprf ptprn ptprr ptprt reefe reeft reene reepe reere refen refer refet reffe refne renee rener renet renfe renne rente repen repet reppe reprt rere- reree reret retee reter retnr rette rnpep rperf rtenn teepe tefe tefen tenen tener tenet tenne tenpn tente tepee tepet teret terne terre tert- teten teter tetr- tette tnftp tntnt treen treer treet trefe treff trene trent trepp trept trere trete trett ttnet ttttt