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: Accepted)

#include <bits/stdc++.h>
using namespace std;
#define REP(i, n) for(int i = 0; i < n; i++)
#define COUT(x) cout<<(x)<<endl
#define dump(x)  cout << #x << " = " << (x) << endl;
using ll = long long;
using P = pair<int,int>;
using Graph = vector<vector<int>>;
using M = map<int,int>;
using PQ = priority_queue<int>;
using PQG = priority_queue<int, vector<int>, greater<int>>;
const int INF = 1e9;
const int MOD = 1e9+7;
const ll LINF = 1e18;

int main() {
  int n,m; cin >> n >> m;
  cout << (m-1)*(n-1) << endl;
  return 0;
}