#include <bits/stdc++.h>
using namespace std;
const int MAXN = 5e5 + 5;
int n;
long long pref[3 * MAXN], A[MAXN];
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n;
for(int i = 1; i <= n; i++)
{
cin >> A[i];
pref[i] = pref[i - 1] + A[i];
}
int hh = (n + 1) / 2;
for(int i = n + 1; i <= 2 * n; i++)
{
pref[i] = pref[i - 1] + A[i - n];
}
for(int i = 2 * n + 1; i <= 3 * n; i++)
{
pref[i] = pref[i - 1] + A[i - 2 * n];
}
long long ans = 0;
deque <pair <long long, int> > Pos;
for(int i = 1; i <= 2 * n; i++)
{
while(!Pos.empty() and Pos.front().second < i - hh + 1)
{
Pos.pop_front();
}
while(!Pos.empty() and Pos.back().first >= pref[i + hh - 1] - pref[i - 1])
{
Pos.pop_back();
}
Pos.push_back(make_pair(pref[i + hh - 1] - pref[i - 1], i));
if(i >= hh)
{
ans = max(ans, Pos.front().first);
}
}
cout << ans << '\n';
}
