Question 24
(SWE) Cards numbered $1$ to $9$ are arranged at random in a row. In a move, one may choose any block of consecutive cards whose numbers are in ascending or descending order, and switch the block around. For example, $916532748$ may be changed to $913562748$. Prove that in at most $12$ moves, one can arrange the $9$ cards so that their numbers are in ascending or descending order.