Problems
Square punch
Square punch
During the Summer School August 2009 the hole punch was tested that makes the square holes. The size of the badge is $n \cdot m$ cells, each of which can be punched. On the diagram $1$ is a punched cell, $0$ is not punched. How many little badges will remain after using a punch?
\InputFile
The first line contains the sizes of the badge $n$ and $m~(1 \le n, m \le 100)$. The next $n$ lines contain a diagram of the punctured badge.
\OutputFile
Print the number of little badges that will remain after using a punch.
\includegraphics{https://static.e-olymp.com/content/58/5844e10a4124a294407807820a57843596a728a0.gif}
Input example #1
5 4 0 0 1 0 0 1 0 0 1 1 1 1 0 0 0 0 1 1 0 0
Output example #1
3
Input example #2
3 3 0 0 0 0 1 0 0 0 0
Output example #2
1