Problem Statement

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

Input Format

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

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

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#Python solution
N = int(raw_input())
sum1 = 0
sum2 = 0
for i in range(N):
    list1 = map(int, raw_input().split(" "))
    sum1 = sum1 + list1[i]
    sum2 = sum2 + list1[N-(i+1)]
print abs(sum1-sum2)