n, *a = map(int, open(0).read().split())
b, c = 0, -float('inf')
f = 0
for i in a:
    if c + i >= b:
        f = 1
    b, c = max(b, c + i), max(c, b - i)
if f == 1:
    print(max(b, c))
else:
    print(c)