p03280 AtCoder Beginner Contest 106 - Garden
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.

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).

Examples

Input

2 2


Output

1


Input

5 7


Output

24
```python
a, b = map(int, input().split())
print(a*b - b - (a-1))
```