#include <bits/stdc++.h>
using namespace std;
int dp[3005][3005];
int main() {
  int n;
  cin >> n;
  long long int arr[n];
  for (int i = 0; i < n; i++) cin >> arr[i];
  int r = 0, l = n - 1;
  for (l = n - 1; l >= 0; --l) {
    for (r = l; r < n; ++r) {
      if (l == r) {
        dp[l][r] = arr[l];
      } else {
        dp[l][r] = max(arr[l] - dp[l + 1][r], arr[r] - dp[l][r - 1]);
      }
    }
  }
  cout << dp[0][n - 1];
  return 0;
}
