#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define sz(x) (int)x.size()
#define ALL(v) v.begin(),v.end()
#define MASK(k) (1LL << (k))
#define BIT(x, i) (((x) >> (i)) & 1)
#define oo (ll)1e18
#define INF (ll)1e9
#define MOD (ll)(1e9 + 7)
using namespace std;
template<class T1, class T2>
bool maximize(T1 &a, T2 b){if(a < b){a = b; return true;} return false;}
template<class T1, class T2>
bool minimize(T1 &a, T2 b){if(a > b){a = b; return true;} return false;}
template<class T1, class T2>
void add(T1 &a, T2 b){a += b; if(a >= MOD) a -= MOD;}
template<class T1, class T2>
void sub(T1 &a, T2 b){a -= b; if(a < 0) a += MOD;}
template<class T>
void cps(T &v){sort(ALL(v)); v.resize(unique(ALL(v)) - v.begin());}
void solve(){
int n; cin >> n;
vector<int> a;
for(int i=0; i<n; i++){
int u; cin >> u;
a.push_back(u);
}
for(int i=0; i<n; i++){
a.push_back(a[i]);
}
ll k = n - n / 2, ans = 0;
vector<ll> pre(2 * n + 3, 0), p(2 * n + 3, 0);
for(int i=1; i<=2*n; i++){
pre[i] = pre[i - 1] + a[i - 1];
if(i >= k) p[i] = pre[i] - pre[i - k];
// cout << p[i] << ' ';
}
deque<int> dq;
for(int i=2*n; i>=k; i--){
if(sz(dq) && dq.front() - i >= k) dq.pop_front();
while(sz(dq) && p[dq.back()] > p[i]) dq.pop_back();
dq.push_back(i);
if(i + k - 1 <= n*2){
maximize(ans, p[dq.front()]);
}
}
cout << ans << '\n';
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0);
// freopen("task.inp", "r", stdin);
// freopen("task.out", "w", stdout);
int t = 1;
// cin >> t;
while(t--){
solve();
}
return 0;
}
