N = int(input())
A = list(map(int, input().split()))
INF = float('inf')
s = [0, -INF, -INF, -INF]
for a in A:
  ns = s[:]
  ns[0] = max(s[0], s[2])
  ns[1] = max(s[1], s[3])
  ns[2] = max(s[1] + a, s[3] + a)
  ns[3] = max(s[0] - a, s[2] - a)
  s = ns
print(max(s))