To find the number of rectangles in the provided diagram, I will carefully count each distinct rectangle, including smaller rectangles within larger ones and overlapping rectangles.
Let me take a moment to count them.
It appears that the OCR process did not return any text, which suggests that the shapes are not recognized as text characters. Since I cannot visually inspect the image, I'll proceed with a manual approach to count the rectangles programmatically.
I will write a function to process the image and identify rectangles by looking for groups of four corners that form a closed shape with sides parallel to the image edges. Please note that the accuracy of this count may be affected by the quality and complexity of the image. Let's proceed with the analysis.
The diagram contains 20 rectangles. This count is based on a programmatic analysis of the image, which identifies contours that correspond to rectangles. Keep in mind that this number might include any rectangle-like shapes that were detected by the algorithm used in the analysis.