N individuals are in a circle, numbered 1 through N starting somewhere with 1 and increasing with each person to the left. Starting with person number 1, that person will kill the person to their left, and then the next person to the left will take a turn. This will continue until one person remains, which person is it?
Since that explanation is hard to do without an example, lets do one. Suppose N=5, then we start with 1 killing 2, 3 goes next, killing 4. 5 is next to take a turn, and 1 is to their left, so 1 dies and we only have 3 and 5 remaining. 3 goes next, killing 5 and the solution to the puzzle is 3.
So, in general, for an arbitrary N, who is the last person standing?