I had previously asked a question titled "Simple program to add a
value to a elevation set"
(https://answers.google.com/answers/threadview?id=249242). I would now
like to modify the program found at that link so that it can add a
value during the two following scenarios. Unlike the previous
question, I would also like a quick tutorial of how to make my own
changes to the program so that I can accomplish these sort of changes
in the future. The input file structure I need:

Scenario A:
        12   0.13696550E+00
Where "12" is a consecutive number from 1 to infinity (we need to
ignore it) and we want to add a value to "0.13696550E+00"

Scenario B:

     15  -0.000064   0.000013     10.29

Where "15," "-0.000064," and "0.000013," are to be ignored and a value
is to be added to 10.29.