Question 95
On a $5 \times 5$ square board, a number of tiles consisting of 4 squares, as shown in the figure, are placed along the grid. Note that the placed tiles may be rotated or flipped over. Furthermore, the placed tiles may be overlapped, but must not protrude beyond the board. Assume that every square of the board is covered with at most two tiles. Find the maximum possible number of squares of the board that are covered by at least one tile.
