The data file must be in the following format: The first line contains the x-coordinate and the y-coordinate of the depot, in that order, separated by spaces or tabs. Each successive line contains the x-coordinate, y-coordinate, and demand of a single customer, separated by spaces or tabs. If distances are to be loaded from a file instead of computed based on coordinates, the x- and y-coordinates may be set to 0 or any other value, but they may not be left blank. Note that the depot has no demand. (A sample data file can be found in the attached file "data20.txt".)