#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define endl '\n'
#define int long long
const int N=1e6+5,inf=2e18,MOD=1e9+7;
int seg[N*4],pref[N],offset=1,a[N];
void update(int idx,int val){
idx+=offset;
seg[idx]=val;
idx/=2;
while(idx>0){
seg[idx]=max(seg[idx*2],seg[idx*2+1]);
idx/=2;
}
}
int query(int node,int qlo,int qhi,int lo,int hi){
if(lo>=qlo && hi<=qhi)return seg[node];
if(lo>qhi || hi<qlo)return -inf;
int mid=(lo+hi)/2;
return max(query(node*2,qlo,qhi,lo,mid),query(node*2+1,qlo,qhi,mid+1,hi));
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n,sum=0,ans=0; cin>>n;
while(offset<N)offset*=2;
for(int i=0;i<n*2;i++){
if(i<n){
cin>>a[i];
sum+=a[i];
}
else{
a[i]=a[i%n];
ans=max(ans,sum-query(1,i-(n%2?n/2-1:n/2),i-1,0,offset-1));
}
pref[i]=a[i];
if(i>0)pref[i]+=pref[i-1];
if(i>=n/2-1)update(i,pref[i]-(i-n/2>=0?pref[i-n/2]:0));
}
cout<<ans;
}
