#include <bits/stdc++.h>
using namespace std;

#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define FOR(i, a, b) for (int i = (a); i<(b); ++i)
#define RFOR(i, b, a) for (int i = (b)-1; i>=(a); --i)
#define MP make_pair
#define PB push_back
#define F first
#define S second
#define FILL(a, b) memset(a, b, sizeof(a))

typedef long long LL;
typedef pair<int, int> PII;
typedef vector<int> VI;

const LL INF = 1e9 + 7;

const int N = 3047;

LL dp[N][N];

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	
	int n;
	cin >> n;
	VI a(n);
	FOR (i, 0, n) cin >> a[i];
	FOR (i, 0, N)
	{
		FOR (j, 0, N) dp[i][j] = -INF * INF;
	}
	dp[0][n - 1] = a[0];
	FOR (i, 0, n)
	{
		LL mx = -INF * INF;
		FOR (j, n - 1 - i, n) mx = max(mx, dp[i][j]);
		RFOR (j, n, i + 1)
		{
			dp[j][j - i] = max(dp[j][j - i], mx + a[j]);
			mx = max(mx, dp[i][n - 1 - i - (n - j)]);
		}
	}
	LL ans = -INF * INF;
	FOR (i, 0, n) ans = max(ans, dp[n - 1][i]);
	cout << ans << '\n';
	
	return 0;
}