b-tree bbbbbb becure beebee beeter berbee berber bereet berere berrer berret bertre berube betere betete betrue bettee better betutu beurre breere brette breuer brubru bruree bubber bububu burbet burbur burcer burree burrer burret burutu butere butter butucu c-cube ceecee cerete ceruce creete cubber cubert cubube cucube cucurb curber curete currer curret curter cutcut cuttee cutter ebbert eburru eebree eerect erbree errett etcetc ettutu eutere r-tree rebbec rebeuc rebute recrue recuer recurb recure recurt retece reteer reteet retere retree retret retter rettur retube returu reuere reuter reutte rubbee rubber rubutu rurutu ruttee rutter rutube t-tree t-tube teebee teetee teeter tercer tercet terete terrer terret terter tertre tetete tetter teucer tr-rec trebce trebur treece treete tretee trette treuce truett tubber turbet turret turtur turucu tururu tuteur tutter tuttut u-tube ureter urette uteute