**Case Study**

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

**Solution**

<?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); ?>