#include <iostream>
#include <limits>
#include <vector>
using namespace std;
int t[4000'000];
void Build(const vector<int>& a, int v, int vl, int vr)
{
if (vl == vr)
{
t[v] = a[vr];
return;
}
int vm = (vl + vr) / 2;
Build(a, v * 2, vl, vm);
Build(a, v * 2 + 1, vm + 1, vr);
t[v] = min(t[v * 2], t[v * 2 + 1]);
}
int Min(int v, int vl, int vr, int l, int r)
{
if (vl > r || l > vr)
return numeric_limits<int>::max();
if (l <= vl && vr <= r)
return t[v];
int vm = (vl + vr) / 2;
return min(Min(v * 2, vl, vm, l, r), Min(v * 2 + 1, vm + 1, vr, l, r));
}
int main()
{
int n;
cin >> n;
vector<int> a(n);
for (int i = 0; i < n; ++i)
cin >> a[i];
vector<int> b(3 * n), pref(3 * n);
for (int i = 0; i < 3 * n; ++i)
{
b[i] = a[i % n];
pref[i] = (i ? pref[i - 1] : 0) + b[i];
}
vector<int> sum(2 * n);
for (int i = 0; i < 2 * n; ++i)
sum[i] = pref[i + (n + 1) / 2 - 1] - (i ? pref[i - 1] : 0);
Build(sum, 1, 0, 2 * n - 1);
int ans = 0;
for (int i = n; i < 2 * n; ++i)
ans = max(ans, Min(1, 0, 2 * n - 1, i - (n + 1) / 2 + 1, i));
cout << ans;
}
