Let $S$ be a number string, and $occ(S,x)$ means the times that number $x$ occurs in $S$.
i.e. $S=(1,2,2,1,3),occ(S,1)=2,occ(S,2)=2,occ(S,3)=1$.
String $u,w$ are matched if for each number $i$, $occ(u,i)=occ(w,i)$ always holds.
i.e. $(1,2,2,1,3)\approx(1,3,2,1,2)$.
Let $S$ be a string. An integer $k$ is a full Abelian period of $S$ if $S$ can be partitioned into several continous substrings of length $k$, and all of these substrings are matched with each other.
Now given a string $S$, please find all of the numbers $k$ that $k$ is a full Abelian period of $S$.