CF884E Binary Matrix

Description

You are given a matrix of size $ n×m $ . Each element of the matrix is either 1 or 0. You have to determine the number of connected components consisting of 1's. Two cells belong to the same component if they have a common border, and both elements in these cells are 1's. Note that the memory limit is unusual!

Input Format

The first line contains two numbers $ n $ and $ m $ ( $ 1

Output Format

Print the number of connected components consisting of 1's.

Explanation/Hint

In the first example the matrix is: `

0001

1010

1000

`It is clear that it has three components. The second example: `

01011111

11100011

`It is clear that the number of components is 2. There are no 1's in the third example, so the answer is 0.