public static int diagonalDifference(List<List<Integer>> arr) {
        var lr = 0;
        var rl = 0;
        var size = arr.size();
        for (int i = 0, j = size - 1; i < size; i++, j--) {
            lr += arr.get(i).get(i);
            rl += arr.get(i).get(j);
        }
        return Math.abs(lr-rl);
    }