A - Bulletin Board /

### 問題文

A 社主催のプログラミングコンテストの開催が決定したので、その告知を会社の掲示板に張り出すことにしました。

### 制約

• 1 \leq H, W \leq N \leq 100
• 入力値はすべて整数である。

### 入力

N
H
W


### 入力例 1

3
2
3


### 出力例 1

2


###   ...
###   ###
...   ###


### 入力例 2

100
1
1


### 出力例 2

10000


### 入力例 3

5
4
2


### 出力例 3

8


Score : 100 points

### 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?

### Constraints

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

### Input

Input is given from Standard Input in the following format:

N
H
W


### 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