Sorry, let me clarify. In order to work out what is going on, you need to evaluate the expression p+p-p. And as the output is "2011" that means you need to work out why the expression evaluates to &p.
My question did not indicate I do not know the answer. I know exactly why it does what it does. The point is to help YOU figure it out.
So have a look at p, work out what it is and what it points at, then if you need to, read the book on character strings again, then you should be able to work out what p, p, p and so on are.