public static int hourglassSum(List<List<Integer>> arr) {
    // Write your code here
        int maxInteger = Integer.MIN_VALUE;
        for (int row = 0; row < arr.size() - 2; row++) {
            for (int col = 0; col < arr.get(row).size() - 2; col++) {
                int topRow = arr.get(row).get(col) + arr.get(row).get(col + 1) + arr.get(row).get(col + 2);
                int bottomRow = arr.get(row + 2).get(col) + arr.get(row + 2).get(col + 1) + arr.get(row + 2).get(col + 2);
                int middleRow = arr.get(row + 1).get(col + 1);
                maxInteger = Math.max(maxInteger, topRow + bottomRow + middleRow);
            }
        }
        return maxInteger;
    }