#include<bits/stdc++.h>

using namespace std;

const int MX = ;

int d[MX][MX],f[MX][MX],g[MX][MX];

int sum[MX];

//#define LOCAL

int main()

{

#ifdef LOCAL

    freopen("in.txt","r",stdin);

#endif

    int n;

    while(scanf("%d",&n),n){

        for(int i = ; i <= n; i++){

            scanf("%d",sum+i);

        }

        for(int i = ; i <= n; i++){

            g[i][i] = f[i][i] = d[i][i] = sum[i];

            sum[i] += sum[i-];

        }

        for(int L = ; L < n; L++){

            for(int i = ; i+L <= n; i++){

                int j = i+L;

                d[i][j] = sum[j] - sum[i-] - min(,min(f[i+][j],g[i][j-]));

                f[i][j] = min(d[i][j],f[i+][j]);

                g[i][j] = min(d[i][j],g[i][j-]);

            }

        }

        printf("%d\n",(d[][n]<<)-sum[n]);

    }

    return ;

}