To determine the value of \( N \) from the diagram representing books on shelves, we would typically count the total number of books or shelves depicted in that diagram. Since I can't see the diagram, I can't provide the exact value of \( N \).
However, the general idea is that \( N \) represents the total number of items (in this case, books or shelves) shown in the diagram. You'll need to count those items based on what is depicted in the image.
If you provide me with the details from the diagram or describe it, I could help you better in estimating \( N \).