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 (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
int main(void){
    /* 変数宣言，ちゃんと初期化しよう */
    int A = 0;
    int B = 0;
    int ans = 0;
    /* 変数宣言終わり */
    
    /* 入力を受け付ける部分*/
    
    // %dはdecimalの略．つまり，入力を10進数として扱うよという意味．
    scanf("%d %d", &A, &B);
    
    /* 入力を受け付ける部分終わり*/
    
    
    /* 何か処理*/
    ans = A*B - A -B +1;
    
    if(1 == 0){
      /* 真の場合の処理 */
      
    }else{
      /* 偽の場合の処理 */
      
    }
    
    for(int i = 0; i < 10; i++){ 
      // i = 0,1,2,3,4,5,6,7,8,9のとき処理される
      
    }
    
    /* 何か処理終わり*/
    
    
    /* 出力する部分*/
    
    printf("%d", ans); // %dの部分にansの値が表示される
    
    /* 出力する部分*/
    
    
    
    return 0;
}