That is quite normal, you should modify your abs line to:
dif = Math.Abs(dif)
Doing that you'll put the absolute value of dif into dif.
See this
link[
^].
The Math.Abs function returns the absolute value of a number passed as parameter.
In that way you can do plenty of things:
dif = Math.Abs(dif)
another_var = Math.Abs(dif)
var3 = Math.Abs(function_call())
...
Good luck!