#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
const int N = 500000;
ll pre[3*N+5];
int a[3*N+5];
deque <pair <int, int>> q;
void ubaci(pair <int, int> x){
while(!q.empty() && q.back().first >= x.first) q.pop_back();
q.push_back(x);
}
int main(){
ios_base::sync_with_stdio(false), cin.tie(0);
cout.precision(10);
cout << fixed;
int n;
cin >> n;
for(int i=1; i<=n; i++){
cin >> a[i];
a[i+n] = a[i+2*n] = a[i];
}
for(int i=1; i<=3*n; i++) pre[i] = pre[i-1] + a[i];
int k = (n+1)/2;
for(int j=n+1-k+1; j<=n+1; j++) ubaci({pre[j+k-1] - pre[j-1], j});
int res = q.front().first;
for(int i=n+2; i<=2*n; i++){
ubaci({pre[i+k-1] - pre[i-1], i});
while(q.front().second < i-k+1) q.pop_front();
res = max(res, q.front().first);
}
cout << res << "\n";
return 0;
}
