**Time limit:**2.00 s**Memory limit:**512 MB

Count the number of rectangles whose each corner square is black.

**Input**

The first input line contains two integer $n$ and $m$: the size of the grid.

Then, there are $n$ lines of length $m$ that describe the grid. Each line consists of characters 0 (white) and 1 (black).

**Output**

Print the number of rectangles whose each corner square is black.

**Constraints**

- $1 \le n,m \le 3000$

**Example**

Input:

`3 4`

0111

0011

0101

Output:

`2`