A9541 | Special Grid

The first line contains two integers $n$ and $m$ $(2<=n,m<=400)$ . Each of the following $n$ lines contain $m$ characters (zeros and ones) — the description of the grid. If the $j$ -th character in the $i$ -th line equals zero, then the node on the $i$ -th horizontal line and on the $j$ -th vertical line is painted white. Otherwise, the node is painted black.

The horizontal lines are numbered starting from one from top to bottom, the vertical lines are numbered starting from one from left to right.

Print a single integer — the number of required triangles.

The figure below shows red and blue triangles. They are the examples of the required triangles in the first sample. One of the invalid triangles is painted green. It is invalid because not all sides go along the grid lines.