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CSES - HIIT Open 2017

HIIT Open 2017

Contest start:2017-05-27 11:00:00
Contest end:2017-05-27 16:00:00

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Grid

Time limit:2.00 s
Memory limit:512 MB

You are given an $n \times m$ grid whose each square is either black or white.

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
Example

Input:
3 4
0111
0011
0101


Output:
2