"Fred Smith" wrote in message
...
You are getting -2 because you are using three minus signs for each
argument. You need only two. The third one is changing your answer to
negative.

....and because there are an odd number of conditional tests, if there were
an even number, it would have worked, as would one, 5 or any other odd
number of dashes (not that I think it should ever be any other number than
2)