Problem:
Score : 100 points

Problem Statement

In K-city, there are n streets running east-west, and m streets running north-south. Each street running east-west and each street running north-south cross each other. We will call the smallest area that is surrounded by four streets a block. How many blocks there are in K-city?

Constraints

2 ≤ n, m ≤ 100

Input

Input is given from Standard Input in the following format:

n m

Output

Print the number of blocks in K-city.

Sample Input 1

3 4

Sample Output 1

6

There are six blocks, as shown below:

Sample Input 2

2 2

Sample Output 2

1

There are one block, as shown below:

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

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <math.h>
#include <functional>
#include <iomanip>
#include <bitset>
#include <numeric>
#include <queue>
#include <map>
#include <cstdint>
using namespace std;
#define rep(i, n) for (int i = 0; i < n; i++)
const long long mod = 1000000007;
typedef long long int ll;
typedef pair<ll, ll> P;
const vector<int> di = { -1, 0, 1, 0 };
const vector<int> dj = { 0, 1, 0, -1 };
const double PI = 3.14159265358979323846;




int main() {

	int n, m;
	cin >> n, m;

	int ans = (n - 1) * (m - 1);

	cout << ans << endl;
	
	return 0;
	
}