def diagonalDifference(arr):
    lr = rl = 0
    n = len(arr)
    for i in range(n):
        lr += arr[i][i]
        rl += arr[i][n-1-i]
    
    return abs(lr - rl)

n = int(input())
arr = []
for _ in range(n):
    arr.append(list(map(int, input().split())))


result = diagonalDifference(arr)

print(result)