Question 97
Consider a $m \times n$ board divided into unit squares. An L-triomino consists of three unit squares, a center square and two leg squares. There is an L-triomino in the top left corner, so that the center square is on the corner field. In one move, the L-Triomino can be rotated around the center of one of the two leg squares by multiples of $90^{\circ}$. For which $m$ and $n$ is it possible that the L-Triomino ends up in the lower right corner after a finite number of such moves?