#include <bits/stdc++.h>
using namespace std;
void setup()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
}
int n, a[1000001];
long long pre[1000001], res;
priority_queue<pair<long long, int>> pq;
int main()
{
setup();
cin >> n;
for (int i = 1; i <= n; ++i)
{
cin >> a[i];
a[i + n] = a[i];
}
for (int i = 1; i <= 2 * n; ++i)
{
pre[i] = a[i] + pre[i - 1];
}
for (int i = 1, j = 1; i <= n; ++i)
{
while (j + n / 2 < i + n)
{
pq.push({pre[j + n / 2] - pre[j], j});
j++;
}
while (!pq.empty() && pq.top().second < i)
{
pq.pop();
}
res = max(res, pre[n] - pq.top().first);
}
cout << res;
return 0;
}
