#include<bits/stdc++.h>
using namespace std;
const int maxn=2e3+10;
int n,a[maxn];
int sum[maxn],f[maxn][maxn];
int main()
{
    cin>>n;
    for(int i=n;i>=1;i--) 
        cin>>a[i]; 
    for(int i=1;i<=n;i++) 
        sum[i]=sum[i-1]+a[i];
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++) 
        {
            int k=3*j; 
            f[i][j]=f[i][j-1]; 
            if(k-2<=i) f[i][j]=max(f[i][j],sum[i]-f[i-k+2][k-2]);
            if(k-1<=i) f[i][j]=max(f[i][j],sum[i]-f[i-k+1][k-1]);
            if(k<=i) f[i][j]=max(f[i][j],sum[i]-f[i-k][k]);
        }
    cout<<f[n][1];
    return 0;
}