At DoorDash, menus are updated daily even hourly to keep them up-to-date. Each menu can be regarded as a tree. When the merchant sends us the latest menu, can we calculate
how many nodes have changed/added/deleted?

Assume each Node structure is as below:

class Node {
String key;
int value;
List children;
}

Assume there are no duplicate nodes with the same key.

Output: Return the number of changed nodes in the tree.

            Existing tree
a(1)
/      
b(2)      c(3)
/     \         
d(4)    e(5)      f(6)

            New tree
a(1)

c(3)

f(66)

a(1) a is the key, 1 is the value
For example, there are a total of 4 changed nodes. Node b, Node d, Node e are automatically set to inactive. The value of Node f changed as well.

          Existing tree
a(1)
/      
b(2‍‍‌‌‌‍‍‌‌‍‍‍‌‍‍‌‌‍)      c(3)
/       \      
d(4)      e(5)      g(7)

              New tree
a(1)
/         
b(2)         h(8)
/    |   \           
e(5)   d(4)   f(6)       g(7)

There are a total of 5 changed nodes. Node f is a newly-added node. c(3) and old g(7) are deactivated and h(8) and g(7) are newly added nodes

followup print out the changes