from collections import deque
N = int(input())
A = list(map(int,input().split()))
if N == 1:
    print(max(A)-min(A))
    exit()

A = deque(A)
ans = 0
while A:
    if A[0]-A[1] > A[-1]-A[-2]:
        ans += A.popleft()-A.popleft()
    else:
        ans += A.pop()-A.pop()
print(ans)