boolean checkSquare(char[][] board) {
		for (int i = 0; i < 3; i++) {
			for (int j = 0; j < 3; j++) {
				int[] result = new int[9];
				for (int n = i * 3; n < (i + 1) * 3; n++) {
					for (int m = j * 3; m < (j + 1) * 3; m++) {
						int temp = (int) board[n][m] - '0';
						if (temp == -2)
							continue; // for '.'
						else if (temp > 9 || temp < 1)
							return false;
						else {
							if (result[temp - 1] == 0)
								result[temp - 1] = 1;
							else
								return false;
						}
					}
				}
			}
		}
		return true;
	}