Question 47
On the first row of a $5 \times 5$ board, $5$ tokens are placed, each having one white face and one black face, all showing the white face. Each token can move from a square to any adjacent one (horizontally or vertically), being flipped over at each move. Moreover, several tokens may occupy the same square. Can a sequence of moves bring the $5$ tokens to the last row, on distinct squares, all of them showing the black face?