Problem Statement

It has been decided that a programming contest sponsored by company A will be held, so we will post the notice on a bulletin board.
The bulletin board is in the form of a grid with N rows and N columns, and the notice will occupy a rectangular region with H rows and W columns.
How many ways are there to choose where to put the notice so that it completely covers exactly HW squares?

Input

Input is given from Standard Input in the following format:
N
H
W

Output

Print the answer.

Constraints

• $1 \leq H, W \leq N \leq 100$
• All values in input are integers.

Sample Input 1

3
2
3

Sample Output 1

2

There are two ways to put the notice, as follows:

...

... ###

Here, # represents a square covered by the notice, and . represents a square not covered.

Sample Input 2

100
1
1

Sample Output 2

10000

Sample Input 3

5
4
2

Sample Output 3

8

见题面 Input 部分

见题面 Output 部分