#include <bits/extc++.h>
using namespace std;
#define int long long
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define mod 1000000007
#define INF LONG_LONG_MAX
#define cmin(a, b) a = min(a, b)
#define cmax(a, b) a = max(a, b)
template<typename T> using ordered_set = __gnu_pbds::tree<T, __gnu_pbds::null_type,
less<T>, __gnu_pbds::rb_tree_tag, __gnu_pbds::tree_order_statistics_node_update>;
template<typename T> using matrix = vector<vector<T>>;
namespace io {
template<typename T, typename F>
istream &operator>>(istream &cin, pair<T, F> &p) {
cin >> p.first >> p.second;
return cin;
}
template<typename T, typename F>
ostream &operator<<(ostream &cout, pair<T, F> &p) {
cout << p.first << ' ' << p.second << '\n';
return cout;
}
template<typename T>
istream &operator>>(istream &cin, vector<T> &a) {
for (T &i: a) cin >> i;
return cin;
}
template<typename T>
ostream &operator<<(ostream &cout, vector<T> &a) {
for (T i: a) cout << i << ' ';
return cout;
}
template<typename T>
istream &operator>>(istream &cin, deque<T> &a) {
for (T &i: a) cin >> i;
return cin;
}
template<typename T>
ostream &operator<<(ostream &cout, deque<T> &a) {
for (T i: a) cout << i << ' ';
return cout;
}
}
using namespace io;
void solution() {
int k = 1, m = 0;
//cin >> k;
while (k--) {
int n, s = 0, l;
cin >> n, l = (n + 1) / 2;
vector<int> a(n), pref(n * 2), dp(n * 2), d(n * 2);
cin >> a;
for (int i = 0; i < n; ++i) pref[i] = pref[i + n] = a[i];
partial_sum(all(pref), pref.begin());
dp[l - 1] = pref[l - 1];
for (int i = l; i < n * 2; ++i) dp[i] = pref[i] - pref[i - l];
multiset<int> ms;
for (int i = l - 1; i < l * 2 - 2; ++i) ms.insert(dp[i]);
for (int i = l * 2 - 2; i < n * 2; ++i) {
ms.insert(dp[i]);
d[i] = *ms.begin();
ms.erase(ms.find(dp[i - l + 1]));
}
for (int i = 0; i < n * 2; ++i) cmax(s, d[i]);
cmax(m, s);
}
cout << m;
}
signed main() {
ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr), cerr.tie(nullptr);
int t = 1;
// cin >> t;
while (t--) {
solution();
cout << '\n';
}
return 0;
}
