def larger(xl, yl):
	if xl[0] > yl[0]: return xl
	else: return yl

N = int(raw_input())
v = map(int, raw_input().split())
sushi = [[0, -1], [v[0], 0]]
for i in range(1, N):
	if sushi[i][1] == i-1:
		sushi.append(larger([sushi[i-1][0]+v[i], i], sushi[i]))
	else:
		sushi.append(larger([sushi[i-1][0]+v[i], i], [sushi[i][0]+v[i], i]))
print sushi[N][0]