Practice Strings and Loops with the exercise "Chess board analyzer"

Learning Opportunities

This puzzle can be solved using the following concepts. Practice using these concepts and improve your skills.

Statement

Goal

Find the winner (W or B) for the given chess board. If there isn't a King in checkmate position output N.

You have to make several assumptions:
- The given boards are legal and are assuming the official Chess rules: https://en.wikipedia.org/wiki/Rules_of_chess
- In every board there is a winner (no draws) or the board is not terminal (the game could be continued)
- An attacked King could be saved only by moving himself to a safe square (not by using another piece from the King's team)
- A safe square is defined as either an empty square not attacked by any opponent's piece, or a square occupied by an opponent's piece that is not protected by any other opponent's piece
- White pawns are moving upwards, while black pawns are moving downwards

Example board:

........
.......k
........
........
........
......R.
.K.....R
........

In this example the white rooks (uppercase R letters) are attacking all the squares the black king (lowercase k letter) could move onto, so the black king is in checkmate position and the white (W) player wins.

Input

8 lines: Each line contains 8 characters, which are representing a row on the board to analyze.

Characters can be:

. - Not occupied square on the board
R - White Rook
N - White Knight
B - White Bishop
Q - White Queen
K - White King
P - White Pawn
r - Black Rook
n - Black Knight
b - Black Bishop
q - Black Queen
k - Black King
p - Black Pawn

Output

W or B for the winning player or N if the game could be continued.

Constraints

Example

Input

........
.......k
........
........
........
......R.
.K.....R
........

Output

Solve it

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