#include <bits/stdc++.h>
using namespace std;
#define int long long
#define INF (int)1e18
#define f first
#define s second
mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());
int n;
vector <int> a, p;
bool check(int x){
for (int i = 1; i <= n; i++){
int last = i - 1;
for (int j = 0; j < 3; j++){
last = lower_bound(p.begin(), p.end(), p[last] + x) - p.begin();
}
if (last < i + n) return true;
}
return false;
}
void Solve()
{
cin >> n;
a.resize(2 * n + 1, 0);
p.resize(2 * n + 4, 0);
for (int i = 1; i <= n; i++){
cin >> a[i];
a[i + n] = a[i];
}
for (int i = 1; i <= 2 * n; i++) p[i] = p[i - 1] + a[i];
p[2 * n + 1] = 1e15;
p[2 * n + 2] = 1e16;
p[2 * n + 3] = 1e17;
int l = 1, r = 1e14;
while (l != r){
int mid = (l + r + 1)/2;
if (check(mid)) l = mid;
else r = mid - 1;
}
cout << l << "\n";
}
int32_t main()
{
auto begin = std::chrono::high_resolution_clock::now();
ios_base::sync_with_stdio(0);
cin.tie(0);
int t = 1;
// cin >> t;
for(int i = 1; i <= t; i++)
{
//cout << "Case #" << i << ": ";
Solve();
}
auto end = std::chrono::high_resolution_clock::now();
auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n";
return 0;
}
