#include<bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
typedef long long ll;
const int maxn = 3000 + 5;
#define _ <<" " <<
int A[maxn];
ll f[maxn][maxn];

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n; cin >> n;
    for (int i = 1;i <= n; ++i) cin >> A[i];
    
    for (int i = 1;i <= n; ++i) {
        for (int j = 1;j <= n; ++j) {
            f[i][j] = LLONG_MIN;
        }
    }

    for (int j = 1;j <= n; ++j) f[1][j] = A[1];
    for (int i = 2;i <= n; ++i) {
        for (int j = 1;j <= n; ++j) {
            if (i-j >= 1) {
                f[i][j] = f[i-j][j] + A[i];
            }
        }
        for (int j = n-1;j >= 1; --j) f[i][j] = max(f[i][j], f[i][j+1]);
    }
    // cout << f[4][1] _ f[3][2] _ f[3][1] << endl;
    ll ans = LLONG_MIN;
    for (int j = 1;j <= n; ++j) ans = max(ans, f[n][j]);
    cout << ans << '\n';
    return 0;
}