# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')
from collections import defaultdict as dd
S = input
R = range
P = print
def I(): return int(S())
def M(): return map(int, S().split())
def L(): return list(M())
def O(): return list(map(int, open(0).read().split()))
def yn(b): print("Yes" if b else "No")
biga = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
smaa = "abcdefghijklmnopqrstuvwxyz"
ctoi = lambda c: ord(c) - ord('a')
itoc = lambda i: chr(ord('a') + i)
inf = 10 ** 18
mod = 998244353
def acc(a):
	b = [0]
	for i in a:
		b.append(b[-1] + i)
	return b

n = I()
a = L()
dp = [-inf] * 3 # 0 not choosed
dp[0] = 0
for i in a:
	ndp = [-inf] * 3
	ndp[0] = 0
	ndp[1] = max(dp[1], max(dp[0], dp[2]) - i)
	ndp[2] = max(dp[2], dp[1] + i)
	dp = ndp
P(max(dp[1], dp[2]))