Given an $n \times m$ grid, calculate the total number of triangles whose vertices are all grid points. The figure below shows a triangle on a $4 \times 4$ grid.

Note that the three vertices of a triangle cannot be collinear.

Input

A single line containing two space-separated positive integers $m$ and $n$.

Output

Output a single positive integer, the number of such triangles.

Constraints

For 30% of the data:

• $1 \le m, n \le 10$

For 100% of the data:

• $1 \le m, n \le 1000$

Examples

Input 1

1 1

Output 1

4

Input 2

2 2

Output 2

76