#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <utility>
#define FAST_IO ios::sync_with_stdio(false);cin.tie(0);
#define pb push_back
#define all(x) begin(x), end(x)
#define space " "
#define TEST_CASES int a; cin >> a; for (int i = 0; i < a; i++) {solve(); cout << endl;}
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count());
void solve() {
int n; cin >> n;
vector<int> vec(n);
for (int i = 0; i < n; i++) {
cin >> vec[i];
vec.pb(vec[i]);
}
int sum = 0;
for (int i = 0; i < (n + 1) / 2; i++) {
sum += vec[i];
}
vector<int> res(n);
vector<vector<int>> keeps(n);
keeps[0].pb(sum);
keeps[(n + 1) / 2].pb(-sum);
for (int i = (n + 1) / 2; i - (n + 1) / 2 + 1 < n; i++) {
sum -= vec[i - (n + 1) / 2];
sum += vec[i];
int j = i - (n + 1) / 2 + 1;
if (i >= n) {
keeps[0].pb(sum);
}
keeps[j].pb(sum);
if (i + 1 != n) {
keeps[(i + 1) % n].pb(-sum);
}
}
multiset<int> s;
for (int i = 0; i < n; i++) {
for (auto x : keeps[i]) {
if (x > 0) {
s.insert(x);
}
else {
s.erase(s.find(-x));
}
}
res[i] = *s.begin();
}
cout << *max_element(all(res));
}
int main() {
FAST_IO;
//freopen("fortmoo.in", "r", stdin);
//freopen("fortmoo.out", "w", stdout);
//TEST_CASES;
solve(); //cout << endl;
/*int a; cin >> a;
for (int i = 1; i <= a; i++){
cout << "Case #" << i << ": ";
solve();
cout << endl;
}*/
}
