Please forgive me if I am trying to act smart but it seems there's another possible answer, which doesn't involve the concepts of geography and calculations and gives this puzzle a kind of a new perspective. Let us assume that this man is standing on a rotating disc. Let's take his start position as A and end position as B. Now it can easily occur that after the man went from A to B, the disc rotated in such a manner that original A and B coincide (the whole idea is that the platform he is running on, is mobile. Ain't it??) Just a thought. Don't kill me on this guys!