This is a problem off of the USACO Training Gateway.

N opaque rectangles (1 <= N <= 1000) of various colors are placed on
a white sheet of paper whose size is A wide by B long. The rectangles
are put with their sides parallel to the sheet's borders. All
rectangles fall within the borders of the sheet so that different
figures of different colors will be seen.

Given rectangle's dimensions, positions, and colour, output the total
area covered by each color.

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This problem is in the graphing section for some reason, and I can't
figure out how to do it using either graphing techniques or normal
ones.

Any suggestions?