(It's in this file, and of course, you're welcome to grab the whole repo, which will enable you to *really* make fun of me.
github.com/GeePawHill/tsd… )
-1 is not a valid position. It's never a valid position (in most programming languages). It's a *sentinel*. It's telling you "there is no answer".
Second, for full control. By providing those two answers, we provide maximum info for the coder to decide what does and doesn't matter.