programming in main.cpp.

Start program by initializing an empty AVL tree. Your program takes one line as input. The input line contains n "modification moves" separated by spaces (1 n 100). The available modification moves are

Aint (Character A followed by an int value between 1 and 100): A3 means insert value 3 into the AVL

tree. If 3 is already in the tree, do nothing.

Dint (Character D followed by an int value between 1 and 100): D3 means delete value 3 into the AVL tree. I

f 3 is not in the tree, do nothing.

Your input is then followed by exactly one finishing move (PRE or POST or IN): If the finishing move is

PRE, then you should print out the tree (in its current situation) in pre-order. If the tree is empty, print out

EMPTY. Otherwise, print out the values separated by spaces. POST and IN are handled similarly.

You don't need to worry about invalid inputs.

Sample input 1: A1 A2 A3 IN

Sample output 1: 1 2 3

Sample input 2: A1 A2 A3 PRE

Sample output 2: 2 1 3

Sample input 3: A1 D1 POST

Sample output 3: EMPTY