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# Diagonal Difference, Algorithm

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

Input Format

The first line contains a single integer, . The next lines denote the matrix’s rows, with each line containing space-separated integers describing the columns.

Constraints

Output Format

Print the absolute difference between the two sums of the matrix’s 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 absolute value function

Current Buffer(saved locally, editable)

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<div class="pull-right"><?php

$handle = fopen ("php://stdin","r"); fscanf($handle,"%d",$n);$a = array();
for($a_i = 0;$a_i < $n;$a_i++) {
$a_temp = fgets($handle);
$a[] = explode(" ",$a_temp);
array_walk($a[$a_i],'intval');
}

$left=0;$right=0;
$count= count($a);
for ($i=0;$i < $count;$i++) { $left +=$a[$i][$i]; $right +=$a[$count-1-$i][$i]; } echo abs($left - \$right); ?></div>

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