n = int(input())
arr = list(map(int, input().split()))
arr.insert(0, 0)
dp = [0]*(n+1)
dp[1] = arr[1]
for i in range(2, n+1):
dp[i] = arr[i]
for j in range(i):
if dp[i] < dp[j] + arr[i-j]:
dp[i] = dp[j] + arr[i-j]
print(dp[n])