Shared code

#include <bits/stdc++.h>

using namespace std;

#define in(a)                                                                  \
  for (auto &x : a)                                                            \
    cin >> x;
#define out(a)                                                                 \
  for (auto x : a)                                                             \
    cout << x << " ";
#define pb push_back
#define int long long
typedef vector<int> vi;
typedef pair<int, int> pii;

void solve() {
  int n;
  cin >> n;
  vi v(n);
  in(v);
  // i j choice
  vector<vector<int>> dp(n, vector<int>(n, 0));
  int k = (n - 1) % 2;
  for (int i = 0; i < n; i++) {
    dp[i][i] = v[i];
  }
  for (int len = 2; len <= n; len++) {
    for (int i = 0; i + len <= n; i++) {
      int j = i + len - 1;
      int k = (n - len) % 2;
      int ok = k ^ 1;
      if (v[i] - dp[i + 1][j] > v[j] - dp[i][j - 1]) {
        dp[i][j] = v[i] - dp[i + 1][j];
      } else {
        dp[i][j] = v[j] - dp[i][j - 1];
      }
    }
  }
  int sum = 0;
  for (auto x : v) {
    sum += x;
  }
  cout << (dp[0][n - 1] + sum) / 2 << '\n';
}

int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);

  int t = 1;
  // cin >> t;

  while (t--) {
    solve();
  }

  return 0;
}