n = int(input())
V = list(map(int, input().split()))

if n == 1:
    print(V[0])
    exit()

dp = [0]*n
dp[0] = V[0]
for i in range(1, n):
    dp[i] = V[i]
    for j in range(i-1):
        dp[i] = max(dp[i], dp[j]+V[i])
#print(dp)
print(max(dp))