0-255
            (root;256)
           /     |    \
          /      |     \
         /       |      \
        /        |       \
 100-200     151-220    220-255
(joe;100)  (sue.3;100)  (bob;35)
    |                      |
 150-200                221-250
(sue.1;100)           (sue.4;100)