Question 4
There are $n+1$ boxes arranged on a circle. One box contains $n$ stones; the others are empty. A move is defined as follows: choose two boxes $A$ and $B$, take two stones from $A$, put one into a box adjacent to $B$, and put the other into a box adjacent to $A$. Note that $A=B$ is allowed. For which $n$ can a sequence of such moves result in each stone being in a separate box?