Your program should work for any of the Digital Elevation
Model files that we looked at on 13th September.

Create a window of an appropriate size for the selected file,
and render the map by setting pixel colours to represent
altitudes in a reasonably pleasant way.

For each large town within the bounds of the selected file,
convert its latitude and longitude to pixel co-ordinates,
and draw a blob along with the town's name at the correct
position in the window.