Eight Queens can be placed on the chess board so that no two Queens are attacking each other.
Four Queens are already pre-placed. What other 4 cells should be occupied by the remaining 4 Queens?
Explanations
Due to the pre-placed 4 Queens, and the additional 4 Queens placed in b3, d7, e2, g6, this is the only symmetrical solution to the Eight Queens Puzzle (up to rotation and reflection).