#include <bits/stdc++.h>
#include <iostream>
using namespace std;
typedef long long ll;
int main() {
ios_base::sync_with_stdio(false); cin.tie(NULL);
int n; cin >> n;
int arr[n];
int pref[n+1]{};
int k = (n + 1) / 2;
for (int i = 0; i < n; i++) {
cin >> arr[i];
}
for (int i = 1; i <= n; i++) {
pref[i] += pref[i-1] + arr[i-1];
}
int val[n]; //segment ending at index
for (int i = 0; i < n; i++) {
int prev = i - k + 1;
int tmp = 0;
if (prev < 0) {
tmp = pref[i+1] + pref[n] - pref[n + prev];
} else {
tmp = pref[i+1] - pref[prev];
}
val[i] = tmp;
}
deque<pair<int, int>> q;
int ans = 0;
for (int i = 0; i < k; i++) {
while (!q.empty() && q.back().first > val[i]) {
q.pop_back();
}
q.push_back({val[i], i});
}
ans = max(ans, q.front().first);
for (int i = k; i < n; i++) {
while (!q.empty() && q.back().first > val[i]) {
q.pop_back();
}
q.push_back({val[i], i});
if (q.front().second == i - k) q.pop_front();
ans = max(ans, q.front().first);
}
cout << ans << '\n';
}
