#include <bits/stdc++.h>//内存：73 M    时间：36 ms 
using namespace std;
typedef long long ll;
int n;
ll a[3010], f[3010][3010];

int main()
{
    scanf("%d", &n);
    ll sum=0;for (int i = 1; i <= n; i++) scanf("%lld", &a[i]), sum += a[i];
    memset(f, 0, sizeof(f));
    for (int i = 1; i <= n; i++) f[i][i] = a[i];
    for (int i = 1; i <= n; i++) a[i] += a[i - 1];
    for (int len = 2; len <= n; len++)
        for (int i = 1; i + len - 1 <= n; i++)
        {
            int j=i + len - 1;
            f[i][j] = a[j]-a[i-1] - min(f[i][j-1],f[i+1][j]);
        }
            
    printf("%lld\n", 2*f[1][n]-sum);
    return 0;
}

#include <bits/stdc++.h>//内存：37 M     时间：25 ms
using namespace std;
typedef long long ll;
int n;
ll a[3010], f[3010*3010/2];
int getid(int i,int j)
{
    int st=n,ed=n-(i-1)+1;
    return (ed+st)*(st-ed+1)/2+(j-i+1);
}   
int main()
{
    scanf("%d", &n);
    ll sum=0;for (int i = 1; i <= n; i++) scanf("%lld", &a[i]), sum += a[i];
    memset(f, 0, sizeof(f));
    for (int i = 1; i <= n; i++) f[getid(i,i)] = a[i];
    for (int i = 1; i <= n; i++) a[i] += a[i - 1];
    for (int len = 2; len <= n; len++)
        for (int i = 1; i + len - 1 <= n; i++)
        {
            int j=i + len - 1;
            f[getid(i,j)] = a[j]-a[i-1] - min(f[getid(i+1,j)], f[getid(i,j-1)]);
        }
            
    printf("%lld\n", 2*f[getid(1,n)]-sum); return 0;
}

#include <bits/stdc++.h>//内存：73 M	时间：36 ms 
using namespace std;
typedef long long ll;
int n;
ll a[3010], f[3010][3010];

int main()
{
    scanf("%d", &n);
    ll sum=0;for (int i = 1; i <= n; i++) scanf("%lld", &a[i]), sum += a[i];
	memset(f, 0, sizeof(f));
    for (int i = 1; i <= n; i++) f[i][i] = a[i];
    for (int i = 1; i <= n; i++) a[i] += a[i - 1];
    for (int len = 2; len <= n; len++)
        for (int i = 1; i + len - 1 <= n; i++)
        {
            int j=i + len - 1;
            f[i][j] = a[j]-a[i-1] - min(f[i][j-1],f[i+1][j]);
        }
            
    printf("%lld\n", 2*f[1][n]-sum);
    return 0;
}

#include <bits/stdc++.h>//内存：37 M     时间：25 ms
using namespace std;
typedef long long ll;
int n;
ll a[3010], f[3010*3010/2];
int getid(int i,int j)
{
    int st=n,ed=n-(i-1)+1;
    return (ed+st)*(st-ed+1)/2+(j-i+1);
}   
int main()
{
    scanf("%d", &n);
    ll sum=0;for (int i = 1; i <= n; i++) scanf("%lld", &a[i]), sum += a[i];
	memset(f, 0, sizeof(f));
    for (int i = 1; i <= n; i++) f[getid(i,i)] = a[i];
    for (int i = 1; i <= n; i++) a[i] += a[i - 1];
    for (int len = 2; len <= n; len++)
        for (int i = 1; i + len - 1 <= n; i++)
        {
            int j=i + len - 1;
            f[getid(i,j)] = a[j]-a[i-1] - min(f[getid(i+1,j)], f[getid(i,j-1)]);
        }
            
    printf("%lld\n", 2*f[getid(1,n)]-sum);
    return 0;
}