Problem:
﻿Score: 100 points

Problem Statement

There is a farm whose length and width are A yard and B yard, respectively. A farmer, John, made a vertical road and a horizontal road inside the farm from one border to another, as shown below: (The gray part represents the roads.)

What is the area of this yard excluding the roads? Find it.

Note

It can be proved that the positions of the roads do not affect the area.

Constraints

A is an integer between 2 and 100 (inclusive).

B is an integer between 2 and 100 (inclusive).

Input

Input is given from Standard Input in the following format:

A B

Output

Print the area of this yard excluding the roads (in square yards).

Sample Input 1

2 2

Sample Output 1

1

In this case, the area is 1 square yard.

Sample Input 2

5 7

Sample Output 2

24

In this case, the area is 24 square yards.

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

#include <bits/stdc++.h>

using namespace std;
#define next _next
#define y1 _y1
#define y2 _y2
#define lowbit(x) (x&(-x))
#define lc ((rt)<<1)
#define rc ((rt)<<1|1)
#define mid  ((l+r)>>1)
#define clr(a, b) memset(a,b,sizeof(a))

#ifdef __LOCAL_DEBUG__
# define _debug(fmt, ...) fprintf(stderr, "\033[94m%s: " fmt "\n\033[0m", \
    __func__, ##__VA_ARGS__)
#define dg(a) cout <<"\033[94m" <<#a << "\033[0m = "<< a << endl;
#else
#define _debug(...) ((void)0)
#define dg(a)((void)0)
#endif

typedef long long ll;
typedef long double ld;
const ld pi = acos(-1);
const int inf = 0x3f3f3f3f;
const ll llinf = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e9 + 7;
const int maxn = static_cast<int>(1e6 + 7);


int main() {
    ios::sync_with_stdio(false), cin.tie(nullptr);
    int A, B;
    while (cin >> A >> B) {
        cout << A * B - (A + B) + 1 << endl;
    }
}