import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

n = ni()
a = na()

inf = 10**18
dp = [-inf, -a[0]]

for i in range(1, n):
    dp = [max(dp[0], dp[1] + a[i]), max(-a[i], max(dp[0] - a[i], dp[1]))]

print(max(dp))