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

n = int(input())

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

result = diagonalDifference(arr)

print(result)