from collections import defaultdict, deque, Counter
# from functools import cache
# import copy
from itertools import combinations, permutations, product, accumulate, groupby, chain
# from more_itertools import distinct_permutations
from heapq import heapify, heappop, heappush
import math
import bisect
from pprint import pprint
from random import randint, shuffle, randrange
import sys
# sys.setrecursionlimit(200000)
input = lambda: sys.stdin.readline().rstrip('\n')
inf = float('inf')
mod1 = 10**9+7
mod2 = 998244353
def ceil_div(x, y): return -(-x//y)

#################################################   

N = int(input())
A = list(map(int, input().split()))
dp = [0, -inf, -inf]
for a in A:
    dp = [0, max(dp[1], dp[0]-a, dp[2]-a), max(dp[2], dp[1]+a)]
print(max(dp[1:]))