b-tree bbbbbb beebee beegee beeter begger berbee berber bereet berege berere berger berrer berret bertre betere betete bettee better breege breere breger bregge brette ebbert eebree egbere egbert eggert erbree errett etgert gbegbe gebbet gebert geegee gegger gerber gerege gerger gerret gertte getter greete greger gregge gregre greter grette gteter r-tree regret reteer reteet retere retree retret retter t-tree teebee teetee teeter terete terrer terret terter tertre tetete tetter treete treget tretee trette