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)

#if 1
  #include <bits/stdc++.h>
#else
  #include "../../../../bits/stdc++.h"
#endif

#define FOR(i,a,b) for(int i = (a);i < (b);i++)
#define RFOR(i,a,b) for(int i = (b)-1;i >= (a);i--)
#define REP(i,n) FOR(i,0,(n))
#define RREP(i,n) RFOR(i,0,(n))

using namespace std;

using pii =  pair<int, int>;
using ll = long long;

#define pb push_back
#define mp make_pair
#define ft first
#define sd second

int n, m;

int main(){
  cin.tie(0);
  
  cin>>n>>m;
  cout<<((n-1)*(m-1))<<endl;

  return 0;
}