**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

- 1 \le n,m \le 3000

# Example

Input:

3 4 0111 0011 0101

Output:

2