#include<bits/stdc++.h>
#define fi first
#define se second
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
const int N=5e5+10;
int sp[N],k[N],naj[N];
int t[N],p[N*2];
void solve(){
int n;
cin>>n;
for(int i=1;i<=n;i++) cin>>t[i];
for(int i=1;i<=n;i++) sp[i]=sp[i-1]+t[i];
for(int i=1;i<=n;i++){
int dl=(n+1)/2;
if(i>=dl) k[i]=sp[i]-sp[i-dl];
else k[i]=sp[i]+sp[n]-sp[n-dl+i];
}
deque<pair<int,int> >deq;
for(int i=n*2;i>=1;i--) p[i]=(i>n?k[i-n]:k[i]);
for(int i=n*2;i>=1;i--){
while(deq.size() and deq.back().fi>=p[i]) deq.pop_back();
if(deq.size() and deq.front().se==i+(n+1)/2) deq.pop_front();
deq.push_back({p[i],i});
if(i<=n) naj[i]=deq.front().fi;
}
int res=0;
for(int i=1;i<=n;i++) res=max(res,naj[i]);
cout<<res<<"\n";
}
int main(){
solve();
}
