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"bits/stdc++.h"
using namespace std;
#define MOD 1000000007

long long int ppow(long long int i, long long int j) {
	long long int res = 1LL;
	while (j) {
		if ((j & 1LL)) {
			res *= i;
			if (res >= MOD) {
				res %= MOD;
			}
		}
		j >>= 1;
		i *= i;
		if (i >= MOD) {
			i %= MOD;
		}
	}
	return res;
}
long long int gcd(long long int a, long long int b) {
	if (a > b) {
		swap(a, b);
	}
	while (a) {
		swap(a, b);
		a %= b;
	}
	return b;
}
long long int lcm(long long int a, long long int b) {
	return a / gcd(a, b)*b;
}
int h;
int w;
int n;
int main() {
	cin >> n;
	cin >> h;
	cin >> w;
	cout << (n - h + 1)*(n - w + 1) << endl;
	return 0;
}