Diagonal Difference

solution.py

'''Problem Statement

You are given a square matrix of size N×N. Calculate the absolute difference of the sums across the two main diagonals.

Input Format

The first line contains a single integer N. The next N lines contain N integers (each) describing the matrix.

Constraints 
1≤N≤100 
−100≤A[i]≤100
Output Format

Output a single integer equal to the absolute difference in the sums across the diagonals.

Sample Input

3
11 2 4
4 5 6
10 8 -12
Sample Output

15
Explanation

The first diagonal of the matrix is:

11
    5
        -12
Sum across the first diagonal = 11+5-12= 4

The second diagonal of the matrix is:

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

'''
def diag_sum(l):
	x,y = [], []
	for i in range(len(l)):
		x.append(l[i][i])
		y.append(l[i][(len(l) - 1) - i]) 
	return [x, y]

a = []
for i in range(input()):
    a.append(map(int, raw_input().split()))

print abs(sum(diag_sum(a)[0]) - sum(diag_sum(a)[1]))