#include <bits/stdc++.h>
#pragma GCC optimize ("Ofast")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<pii, int> piii;
typedef pair<ll, ll> pll;
#define debug(x) cerr<<#x<<'='<<(x)<<endl;
#define debugp(x) cerr<<#x<<"= {"<<(x.first)<<", "<<(x.second)<<"}"<<endl;
#define debug2(x, y) cerr<<"{"<<#x<<", "<<#y<<"} = {"<<(x)<<", "<<(y)<<"}"<<endl;
#define debugv(v) cerr<<#v<<" : ";for (auto x:v) cerr<<x<<' ';cerr<<endl;
#define all(x) x.begin(), x.end()
#define pb push_back
#define kill(x) return cout<<x<<'\n', 0;
const ld eps=1e-7;
const int inf=1000000010;
const ll INF=10000000000000010LL;
const int mod = 1000000007;
const int MAXN = 500010, LOG=20;
int n, m, k, u, v, x, y, t, a, b, ans, sum;
int A[MAXN*2];
deque<int> dq;
int main(){
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
cin>>n;
m=(n+1)/2;
for (int i=1; i<=n; i++){
cin>>A[i];
A[n+i]=A[i];
}
for (int i=1; i<=2*n; i++) A[i]+=A[i-1];
for (int i=1; i<=n; i++) A[i]=A[i+m]-A[i];
for (int i=1; i<=n; i++) A[i+n]=A[i];
//for (int i=1; i<=2*n; i++) cerr<<A[i]<<' ';cerr<<endl;
for (int i=1; i<=2*n; i++){
while (dq.size() && A[dq.front()]>A[i]) dq.pop_front();
dq.push_front(i);
if (dq.back()<=i-m) dq.pop_back();
if (i>=m) ans=max(ans, A[dq.back()]);
}
cout<<ans<<'\n';
return 0;
}
