fn diagonalDifference(arr: &[Vec<i32>]) -> i32 {
   let n = arr.len();

    let mut left2right = 0;
    let mut right2left = 0;
    for i in 0..n {
        left2right += *arr[i as usize].get(i as usize).unwrap();
        right2left += *arr[i as usize].get(n - 1 - i as usize).unwrap();
    }

    (left2right - right2left).abs()
}