Chef and Pepperoni Pizza

Chef has a pepperoni pizza in the shape of a $N \times N$ grid; both its rows and columns are numbered $1$ through $N$. Some cells of this grid have pepperoni on them, while some do not. Chef wants to cut the pizza vertically in half and give the two halves to two of his friends. Formally, one friend should get everything in the columns $1$ through $N/2$ and the other friend should get everything