#include <bits/stdc++.h>
using namespace std;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int length;
cin >> length;
vector<int> values(length);
for (int index = 0; index < length; index++) cin >> values[index];
int window_size = (length + 1) / 2;
vector<int> window_totals(length);
int total = 0;
for (int index = 0; index < window_size - 1; index++) {
total += values[index];
}
for (int index = 0; index < length; index++) {
total += values[(index + window_size - 1) % length];
window_totals[index] = total;
total -= values[index];
}
int maxima = -1;
deque<pair<int, int>> window;
for (int index = length - window_size + 1; index < length; index++) {
int value = window_totals[index];
while (!window.empty() && window.back().first > value) {
window.pop_back();
}
window.emplace_back(value, index);
}
for (int index = 0; index < length; index++) {
int value = window_totals[index];
while (!window.empty() && window.back().first > value) {
window.pop_back();
}
window.emplace_back(value, index);
maxima = max(maxima, window.front().first);
if (window.front().second == (index - window_size + 1 + length) % length) {
window.pop_front();
}
}
cout << maxima << "\n";
return 0;
}
