Alex is playing a game with Ball. There is a blank matrix $M$ with $n$ lines and $n$ columns. Alex and Ball take turns to mark one of the matrix elements with his own sign (Alex’s sign is called $A$ and Ball’s sign is called $B$). Ball goes first.
After a round of game (a round means that Ball and Alex operates once each in order), if there exists a permutation $p[1..n]$ satisfies that for each $ i \in [1,n]$,$M[i][p[i]]=A$, Alex wins immediately.
After $\lfloor n^2 /2 \rfloor$ rounds, if Alex hasn’t won, Ball wins instead.
Notice that whenever anyone tries to mark a marked matrix element(because of forgetting), he will lose the game immediately.
Sly Ball thinks of a way to interfere Alex. He decides to operate long time after the Alex’s last operation so that Alex may forget about the previous operations.
Now you get this message and want to know two things for a given $n$:
- whether Alex has winning strategy if he remembers all the previous operations
- whether Alex has winning strategy if he forgets all the previous operations, and only knows Ball's last operation each time.
Ball always knows all their previous operations.