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

For example, the square matrix 'arr' is shown below:

1 2 3
4 5 6
9 8 9  

The left-to-right diagonal = 1+5+9 = 15

. The right to left diagonal = 3+5+9 = 17.

Their absolute difference is |15  - 17| = 2

Input Format

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

Constraints:-1<=N=1000, -100<=arr[i][j]<=100

Output Format

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