N = int(input())
A = list(map(int, input().split()))

ans = 0
l = 0
r = N*2 - 1
for _ in range(N):
    x = A[l] - A[l+1]
    y = A[r] - A[r-1]
    if x >= y:
        ans += x
        l += 2
    else:
        ans += y
        r -= 2
print(ans)