// compile: g++ -o data data.cpp -O3 -std=gnu++20 -Wall -Wextra -Wshadow -D_GLIBCXX_ASSERTIONS -ggdb3 -fmax-errors=2 -DLOCAL
// run: ./data < data.in
#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#ifdef LOCAL
#include <debug/codeforces.h>
#define debug(x...) {_variables(#x);_print(x);}
#else
#define debug(x...)
#endif
template<typename...Args> void print_(Args...args){((cout<<args<<" "),...)<<endl;}
#define rep(i,a,b) for(int i=(a);i<(b);++i)
#define sz(v) ((int)(v).size())
#define print(...) print_(__VA_ARGS__);
#define INTINF (int)(9223372036854775807)
#define int long long
#define MAXN 5010

int n, a[MAXN], s[MAXN];
int dp[MAXN][MAXN];

int get(int l, int r) {
    int days = r - l + 1;
    return 2 * s[days >> 1] + ((days & 1) * (a[(days >> 1) + 1]));
}

int32_t main() {
    ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

    cin >> n;
    for (int i = 1; i <= n; ++i) cin >> a[i], s[i] = s[i-1] + a[i];
    for (int i = 2; i <= n; ++i) {
        for (int j = 1; j < i; ++j) {
            dp[i][i] = max(dp[i][i], dp[j][j] + get(j+1, i-1));
            dp[i][j] = dp[i-1][j] + a[min(i-j, n+1-i)];
        }
    }
    int ans = 0;
    for (int i = 1; i <= n; ++i) ans = max(ans, dp[n][i]);
    cout << ans << endl;

    return 0;
}