Given a coordinate grid of size $n \times m$, count the number of triplets of points on the grid such that the three points form a triangle. In other words, count the number of sets of points $A(x_A, y_A), B(x_B,y_B), C(x_C,y_C)$ where $1 \le x_i \le n$ and $1 \le y_i \le m$, and the three points form a triangle.
### Input
- A single line containing two integers $n, m$.
### Output
- Print the number of triplets of points.
### Constraints
- $1 \le n,m \le 1000$.
### Sample test
Input
```
2 3
```
Output:
```
18
```
