public void checking_bfs(char[][] board, int x, int y) {
		Queue<Integer> que = new LinkedList<Integer>();
		que.add(x * board[0].length + y);

		int n;
		while (!que.isEmpty()) {
			n = que.remove();
			x = n / board[0].length;
			y = n % board[0].length;
			board[x][y] = '+';

			if (x > 0 && board[x - 1][y] == 'O')
				que.add(n - board[0].length);

			if (x < board.length - 1 && board[x + 1][y] == 'O')
				que.add(n + board[0].length);

			if (y > 0 && board[x][y - 1] == 'O')
				que.add(n - 1);

			if (y < board[0].length - 1 && board[x][y + 1] == 'O')
				que.add(n + 1);
		}
	}