#include <bits/stdc++.h>
using namespace std;
 
int main() {
    int n;
    cin >> n;
    vector<int> cards(n);
    for (int i = 0; i < n; i++) cin >> cards[i];
 
    vector<vector<int>> dp(n, vector<int>(n, 0));
    for (int i = 0; i < n; i++) dp[i][i] = cards[i];
 
    for (int len = 2; len <= n; len++) {
        for (int i = 0; i + len - 1 < n; i++) {
            int j = i + len - 1;
            dp[i][j] = max(cards[i] - dp[i + 1][j], cards[j] - dp[i][j - 1]);
        }
    }
 
    cout << dp[0][n - 1] << endl;
   return 0;
}
 
 
 

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