n = int(input().strip())
arr = []

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

def diagonalDifference(arr):
    abs_diff = 0
    left_diag = 0
    right_diag = 0
    k = len(arr) - 1 

    for i in range(len(arr)):
        left_diag += arr[i][i]
        right_diag += arr[i][k]
        k -= 1
    
    abs_diff = abs(right_diag - left_diag)
    return abs_diff

result = diagonalDifference(arr)
print(result)