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