Question 144
Marwan has chosen 8 cells of the $8 \times 8$ chessboard such that no two lie in the same column or in the same row (we call this a general configuration). On each step Hamza chooses 8 cells in general configuration and puts coins on them. Then Marwan shows all coins that are outside the cells chosen by Marwan. If Marwan shows an even number of coins then Hamza wins, otherwise Hamza removes all coins and makes the next move. Find the minimal number of moves that Hamza needs to guarantee the win (Hamza $\gt$ Marwan).