Description

Given an $N \times M$ grid, compute how many triangles have all three vertices at grid points. Note that the three points of a triangle must not be collinear.

Input Format

The input consists of one line containing two space-separated positive integers $M$ and $N$.

Output Format

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

2 2

76

Hint

Constraints

For all test points, $1 \le N, M \le 1000$.

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