def diagonalDifference(arr):
    left, right = 0, 0
    for i in range(len(arr)):
        for j in range(len(arr[i])):
            if i == j:
                left += arr[i][j]
            if j == len(arr[i]) - 1 - i:
                right += arr[i][j]
    return abs(left - right)