#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(x) begin(x), end(x)
#define sz(x) (int)x.size()
#define pb push_back
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
int n; cin >> n;
vector<int> a(2*n+1);
for(int i=1; i<=n; i++) cin >> a[i];
for(int i=n+1; i<=2*n; i++) a[i] = a[i-n];
vector<int> p(2*n+1);
for(int i=1; i<=2*n; i++){
p[i] = a[i] + p[i-1];
}
int k = (n+1)/2;
vector<int> b(2*n+1);
for(int i=k; i<=2*n; i++){
b[i] = p[i] - p[i-k];
}
for(int i=1; i<k; i++){
b[i] = b[i+n];
}
deque<int> d;
int ans = 0;
for(int i=1; i<=k; i++){
while(!d.empty() and d.back() > b[i]) d.pop_back();
d.push_back(b[i]);
}
ans = max(ans, d.front());
for(int i=k+1; i<=2*n; i++){
if(!d.empty() and d.front() == b[i-k]) d.pop_front();
while(!d.empty() and d.back() > b[i]) d.pop_back();
d.push_back(b[i]);
ans = max(ans, d.front());
}
cout << ans;
}
