// fahadmd16(IIEST Shibpur)
#include<bits/stdc++.h>
using namespace std;

#define ll                                      long long
#define pb                                      push_back
#define pf                                      push_front
#define eb                                      emplace_back
#define mp                                      make_pair
#define ff                                      first
#define ss                                      second
#define db                                      double
#define pll                                     pair<ll, ll>
#define ALL(a)                                  (a).begin(),(a).end()
#define endl                                    "\n"

#define forn(i, n) for (ll i = 0; i < n; i++)
#define forn1(i, n) for (ll i = 1; i < n; i++)
#define ford(i, n) for (ll i = n - 1; i >= 0; i--)
#define ford1(i, n) for (ll i = n - 1; i >= 1; i--)
#define forab(i, a, b) for(ll i = a; i < b; i++)
#define forabd(i, a, b) for(ll i = a; i >= b; i--)
#define eps 1e-10

#define debug(...) fprintf(stderr, __VA_ARGS__), fflush(stderr)


#define IOS ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)

#define trace1(x)                cout<<#x<<": "<<x<<endl
#define trace2(x, y)             cout<<#x<<": "<<x<<" | "<<#y<<": "<<y<<endl
#define trace3(x, y, z)          cout<<#x<<": "<<x<<" | "<<#y<<": "<<y<<" | "<<#z<<": "<<z<<endl
#define trace4(a, b, c, d)       cout<<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<endl
#define trace5(a, b, c, d, e)    cout<<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<" | "<<#e<< ": "<<e<<endl
#define trace6(a, b, c, d, e, f) cout<<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<" | "<<#e<< ": "<<e<<" | "<<#f<<": "<<f<<endl
#define tracen( x , n ){ cout<<(#x)<<":";for(int i=0;i<n;i++)cout<<(#x)<<"["<<i<<"]:"<< x[i] << "    "; cout<<endl;}
#define tracenm( x , n , m ){ cout<<(#x)<<endl;for(int i=0;i<n;i++){ cout<<"Row #"<<i<<":"; for(int j=0;j<m;j++) cout<<x[i][j]<<"     "; cout << endl;}}
#define trace(v){ cout<<#v<<": ";for(auto it=v.begin();it!=v.end();it++)cout<<*it<<" ";cout<<endl;}
using namespace std;



const ll sz = 3e3 + 2;
const ll mod = 1e9 + 7;
const db PI = acos(-1);



typedef vector<ll> VL;
typedef vector<pll > VLL;
typedef vector<vector<ll> > VVL;



ll power(ll n, ll k, ll m) {
	ll ans = 1;
	while (k) {
		if (k & 1)ans = (ans * n) % m;
		k /= 2;
		n = (n * n) % m;
	}
	return ans;
}
ll dp[sz][sz][2]; // dp[i][j][type] -- optimal way to play the game with values from i,j and type denotes the turn of the player.
ll n;
ll a[sz];

void solver() {
	cin >> n;
	forn(i, n)cin >> a[i];

	forab(L, 1, n + 1) {
		forn1(i, n + 2 - L) {
			ll j = i + L - 1;
			if (i == j) {
				dp[i][j][0] = a[i - 1];
				dp[i][j][1] = -a[i - 1];
			}
			else {
				dp[i][j][0] = dp[i + 1][j][1] + a[i - 1];
				dp[i][j][0] = max(dp[i][j][0], dp[i][j - 1][1] + a[j - 1]);
				dp[i][j][1] = dp[i + 1][j][0] - a[i - 1];
				dp[i][j][1] = min(dp[i][j][1], dp[i][j - 1][0] - a[j - 1]);
			}
		}
	}


	cout << dp[1][n][0] << endl;

	// forn(i, n + 1) {
	// 	forn(j, n + 1) {
	// 		trace4(i, j, dp[i][j][0], dp[i][j][1]);
	// 	}
	// }


}


int main() {

	IOS;
	ll T = 1; //cin >> T;


	forn1(i, T + 1) {
		clock_t z = clock();
		solver();
		debug("Total Time: %.3f\n", (double)(clock() - z) / CLOCKS_PER_SEC);
	}
	return 0;
}

Measured memory_bytes: 139648