#include<bits/stdc++.h>
using namespace std;
const int MAXN=5e5+5;
int pref[MAXN*2],A[MAXN];
deque<int> dq;
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n;
cin>>n;
for(int i=1;i<=n;i++)
{
cin>>pref[i];
pref[i+n]=pref[i];
}
for(int i=1;i<=n*2;i++) pref[i]+=pref[i-1];
int ans=0;
for(int i=(n+1)/2;i<=n*2;i++)
{
A[i]=pref[i]-pref[i-(n+1)/2];
while(!dq.empty()&&A[i]<A[dq.back()]) dq.pop_back();
dq.push_back(i);
if(dq.front()==i-(n+1)/2) dq.pop_front();
if(i>=(n+1)/2*2-1) ans=max(ans,A[dq.front()]);
}
cout<<ans;
}
