'''
Given a square matrix, calculate the absolute difference between the sums of its diagonals.

For example, the square matrix

is shown below:

1 2 3
4 5 6
9 8 9  

The left-to-right diagonal =
. The right to left diagonal = . Their absolute difference is

.

Function description

Complete the

function in the editor below.

diagonalDifference takes the following parameter:

    int arr[n][m]: an array of integers

Return

    int: the absolute diagonal difference

Input Format

The first line contains a single integer,
, the number of rows and columns in the square matrix .
Each of the next lines describes a row, , and consists of space-separated integers

.

Constraints

Output Format

Return the absolute difference between the sums of the matrix's two diagonals as a single integer.

Sample Input

3
11 2 4
4 5 6
10 8 -12

Sample Output

15

Explanation

The primary diagonal is:

11
   5
     -12

Sum across the primary diagonal: 11 + 5 - 12 = 4

The secondary diagonal is:

     4
   5
10

Sum across the secondary diagonal: 4 + 5 + 10 = 19
Difference: |4 - 19| = 15

Note: |x| is the absolute value of x
'''

import math
import os
import random
import re
import sys

#
# Complete the 'diagonalDifference' function below.
#
# The function is expected to return an INTEGER.
# The function accepts 2D_INTEGER_ARRAY arr as parameter.
#

def diagonalDifference(arr):
    RtL = 0
    LtR = 0
    for x in range(len(arr)):
        RtL += arr[x][x]
        LtR += arr[len(arr)-(x+1)][x]
    return abs(RtL-LtR)
