To go up OR down counts as 0.5 .
You have to go up to start.
You are done before you have to go back down the other end.
So 785.5 is correct, assuming there are 786 mountains to cross.
As for this thread, "Hello, this is my first post; I've been lurking for a while..." has become the internet equivalent of "I never used to believe any of the stories in Penthouse Forum, until..." . Sketchy at best, though lots of fun to read sometimes.