During the Summer School August 2009 the hole punch was tested that makes the square holes. The size of the badge is n⋅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?
The first line contains the sizes of the badge n and m (1≤n,m≤100). The next n lines contain a diagram of the punctured badge.
Print the number of little badges that will remain after using a punch.