Problem:
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

Output

Print the answer.

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

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include "iostream"
#include "algorithm"
#include "vector"
#include "string"
#include "cmath"
typedef long long ll;
using namespace std;

int main(int argc, char const *argv[]) {
  ll NN, HH, WW;

  std::cin >> NN >> HH >> WW;

  ll row = (NN - HH) + 1;
  ll col = (NN - WW) + 1;

  if (row < 0 || col < 0) {
    std::cout << 0 << '\n';
  }else{
    std::cout << row * col << '\n';
  }

  return 0;
}