static void printMaxHourglassSum(List> arr){ //System.out.println("arr " + (arr.get(0)).get(0));

    ArrayList<Integer> arrSum = new ArrayList<>();
    for(int row=0; row<6; row++){
        for(int col=0; col<6; col++){
            //System.out.println("row: " + row + ", col: " + col);
            int skipIdx = 0;
            int temp = 0;
            if(row<=3 && col<=3)
            {
                for(int i=row; i<row+3; i++){
                    for(int j=col; j<col+3; j++){
                        skipIdx++;
                        //System.out.println("idx: " + idx);
                        // System.out.println("i: " + i 
                        //     + ", j: " + j 
                        //     + "= " + (arr.get(i)).get(j));

                        if(skipIdx==4 ||skipIdx==6){
                            continue;
                        }

                        temp += (arr.get(i)).get(j);
                    }
                }
                //System.out.println("temp: " + temp);
                arrSum.add(temp);
            }
        }
    }

    for(int i=0; i<arrSum.size(); i++){
        //System.out.println("arrSum: " + arrSum.get(i));
    }

    Collections.sort(arrSum);

    System.out.println(arrSum.get(arrSum.size()-1));
}