import sys
from itertools import batched


def input(): return sys.stdin.readline().rstrip('\n')


def main():
    n = int(input())
    *a, = map(int, input().split())
    a = [p - q for p, q in batched(a, 2)]
    ans = sm = sum(a)
    for v in reversed(a):
        sm -= 2 * v
        ans = max(ans, sm)
    print(ans)


if __name__ == '__main__':
    main()