// https://oj.uz/problem/view/BOI15_hac
#include <iostream>
#include <vector>
#include <deque>
typedef std::pair<int,int> ii;
int main() {
int n;
std::cin >> n;
std::vector<int> value (n), segvalue (n);
for (int& i : value) std::cin >> i;
value.insert(value.end(), value.begin(), value.end());
// for (int& i : value) std::cout << i << ' ';
for (int i = 1; i < 2 * n; ++i) value[i] += value[i-1]; // conv to sum table
int seglen = (n+1)/2;
for (int i = 0; i < n; ++i) segvalue[i] = value[i+seglen] - value[i];
value.clear(); // no longer need value
segvalue.insert(segvalue.end(), segvalue.begin(), segvalue.end());
std::deque<ii> candidatepairs; // need to calculate min of windows, then pick the max of min's
// ii : index -> value (in segvalue)
for (int i = 0; i < seglen-1; ++i) {
while ((!candidatepairs.empty()) && candidatepairs.back().second >= segvalue[i])
candidatepairs.pop_back();
candidatepairs.emplace_back(i, segvalue[i]);
}
int result = -1; // need to get max
for (int i = 0; i < n; ++i) {
// segment [i .. i+seglen)
// insert i+seglen-1
int j = i+seglen-1;
while ((!candidatepairs.empty()) && candidatepairs.back().second >= segvalue[j])
candidatepairs.pop_back();
candidatepairs.emplace_back(j, segvalue[j]);
// delete anything < i
while ((!candidatepairs.empty()) && candidatepairs.front().first < i) candidatepairs.pop_front();
// and get the min
result = std::max(result, candidatepairs.front().second);
}
std::cout << result << '\n';
}
