import java.util.*; class Main { public static void main(String[] args) { List<List<Integer>> arr = new ArrayList<>(); arr.add(Arrays.asList(1,2,3)); arr.add(Arrays.asList(4,5,6)); arr.add(Arrays.asList(9,8,9)); int firstDiagonal = 0; int secondDiagonal = 0; int length = arr.size(); for(int i = 0; i < length; i++){ firstDiagonal += arr.get(i).get(i); secondDiagonal += arr.get(i).get(length - i - 1); } System.out.println(Math.abs(firstDiagonal - secondDiagonal)); } }