from collections import deque
N = int(input())
A = deque(list(map(int,input().split())))
s = 0
while len(A) > 0:
    if (A[-1] - A[-2]) > (A[0] - A[1]):
        s += A.pop() - A.pop()
    else:
        s += A.popleft() - A.popleft()
print(s)