Groups and the Group Axioms · Superchallenge problem

In a group, suppose $r,s$ satisfy $r*r*r=e$, $s*s=e$, and $s*r*s=r*r$. Writing $t=r*s*r^{-1}*s$, express $t$ as $r^n$ for some $n\in\{0,1,2\}$.