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}