private static void calculateSum(List<List<Integer>> arr) {
    int max = Integer.MIN_VALUE;
    for(int rowidx=0;rowidx<=3;rowidx++) {
        for(int colidx=0;colidx<=3;colidx++) {
            List<Integer> row1 = arr.get(rowidx);
            List<Integer> row2 = arr.get(rowidx+1);
            List<Integer> row3 = arr.get(rowidx+2);
            int row1sum = row1.get(colidx) + row1.get(colidx+1) + row1.get(colidx+2);
            int row2sum = row2.get(colidx+1);
            int row3sum = row3.get(colidx) + row3.get(colidx+1) + row3.get(colidx+2);
            max = Math.max(row1sum + row2sum + row3sum, max);
        }
    }
    System.out.println(max);
}