EMPTY=0
BLACK=1
WHITE=-1


class Go:
	## Initializes self.board to a list[r][c]=EMPTY.
	def __init__(self,boardSize=19):
		self.boardSize=boardSize
		self.board=[[EMPTY]*self.boardSize for x in range(boardSize)]

	## Executes a move.
	#
	#  Doesn't check for kos. Suicide not allowed.
	#
	#  @param color BLACK or WHITE
	#  @return True on success, False on failure (illegal move)
	def move(self,color,row,col):
		if self.board[row][col]!=EMPTY: return False

		self.board[row][col]=color

		# capture neighbors
		for r,c in ((-1,0),(1,0),(0,-1),(0,1)):
			self.temp=[[False]*self.boardSize for x in self.board]
			if not self._floodFill(-color,row+r,col+c): self._remove()

		# check for suicide
		self.temp=[[False]*self.boardSize for x in self.board]
		if not self._floodFill(color,row,col):
			self.board[row][col]=EMPTY
			return False
		return True

	## Checks for liberties of a stone at given coordinates.
	#
	#  The stone's group is marked with True in self.temp, ready for capture if needed. Recursively called for stone's neighbors.
	#
	#  @return True if alive, False if captured
	def _floodFill(self,color,row,col):
		if col<0 or col>=self.boardSize or row<0 or row>=self.boardSize: return False # out of range
		if self.temp[row][col]: return False # already visited
		if self.board[row][col]==EMPTY: return True # found a liberty
		if self.board[row][col]!=color: return False # opponent's stone
		self.temp[row][col]=True # set visited
		return self._floodFill(color,row,col-1) or self._floodFill(color,row,col+1) or self._floodFill(color,row-1,col) or self._floodFill(color,row+1,col) # check neighbors

	## Removes stones at coordinates marked with True in self.temp.
	def _remove(self):
		for r in range(self.boardSize):
			for c in range(self.boardSize):
				if self.temp[r][c]: self.board[r][c]=EMPTY


def exportBoard(board):
	substitutions={EMPTY:".", BLACK:"X", WHITE:"O"}
	return "\n".join("".join(substitutions.get(x,"?") for x in row) for row in board)