#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 3e5 + 5;
const int inf = 1e9;
const int mod = 1e9 + 7;
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n; cin >> n;
vector<int> a(2 * n);
int k = (n + 1) / 2;
for (int i = 0; i < n; i++) {
cin >> a[i];
a[i + n] = a[i];
}
for (int i = 1; i < 2 * n; i++) a[i] += a[i - 1];
vector<int> v;
for (int i = k; i < n + 2 * k - 1; i++) v.push_back(a[i] - a[i - k]);
int x = v.size();
deque<int> dq;
for (int i = 0; i < k; i++) {
while (!dq.empty() && v[dq.back()] > v[i]) dq.pop_back();
dq.push_back(i);
}
int ans = v[dq.front()];
for (int i = k; i < x; i++) {
while (!dq.empty() && v[dq.back()] > v[i]) dq.pop_back();
while (!dq.empty() && i - dq.front() >= k) dq.pop_front();
dq.push_back(i);
smax(ans, v[dq.front()]);
}
cout << ans << en;
return 0;
}
