Task

You are given a chessboard with several rooks and bishops placed on some of its squares. How many unoccupied squares are there that are not under attack of any chess piece?

Here, the standard rules are applied: a square is under attack of a rook or a bishop only if all squares between the piece and the current square are unoccupied.

Input/Output

• [input] integer array chessboard

matrix of size 8x8 containing numbers {-1, 0, 1} which represents chess pieces placement:

-1 -> bishop, 0 -> empty square, 1 -> rook

• [output] an integer

number of safe squares on the board.