from collections import deque

n = int(input())
A = deque(map(int, input().split()))

ans = 0
for _ in range(n):
    if A[0] - A[1] >= A[-1] - A[-2]:
        ans += A[0] - A[1]
        A.popleft()
        A.popleft()
    else:
        ans += A[-1] - A[-2]
        A.pop()
        A.pop()
print(ans)