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++ (GCC 9.2.1) (judge verdict: Accepted)


#include <stdio.h>
#include <string.h>
#include <limits.h>
#include <math.h>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <bitset>

typedef unsigned long long ULLONG;
typedef long long LLONG;
static const LLONG MOD_NUM = 1000000007; //998244353;

template<class _T> static void get(_T& a) {
	std::cin >> a;
}
template<class _T> static void get(_T& a, _T& b) {
	std::cin >> a >> b;
}
template<class _T> static void get(_T& a, _T& b, _T& c) {
	std::cin >> a >> b >> c;
}
template <class _T> static _T tp_abs(_T a) {
	if (a < (_T)0) {
		a *= (_T)-1;
	}
	return a;
}

static void exec();

int main()
{
	exec();
	fflush(stdout);
	return 0;
}

static void exec()
{
	int n, m;
	get(n, m);
	printf("%d\n", (n - 1) * (m - 1));
}