#include <bits/stdc++.h>
#define int long long
using ld = long double;
#define pr pair<int, int>
#define pb push_back
using namespace std;
const int INF = 1e18+1, MOD = 998244353, MAXN = 4e5+5, MAXA = 41;
void solve() {
int n;
cin >> n;
vector<int> a(n);
for (auto& i : a) cin >> i;
for (int i = 0; i < n; i++) a.pb(a[i]);
int k = (n+1) / 2;
int sum = 0;
for (int i = 0; i < k-1; i++) {
sum += a[i];
}
vector<int> sums;
for (int i = k-1; i < n+k-1; i++) {
sum += a[i];
sums.pb(sum);
sum -= a[i-k+1];
}
deque<int> order;
multiset<int> cur;
for (int i = n-k+1; i < n; i++) {
order.pb(sums[i]);
cur.insert(sums[i]);
}
int res = 0;
for (int i = 0; i < n; i++) {
cur.insert(sums[i]);
order.pb(sums[i]);
res = max(res, *cur.begin());
cur.erase(cur.find(order.front()));
order.pop_front();
}
cout << res;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
// int T;
// cin >> T;
// while (T--)
solve();
return 0;
}
