#include <bits/stdc++.h>
#define fi first
#define se second
#define pii pair<int, int>
#define pb push_back
#define ll long long
#define TIME (1.0 * clock() / CLOCKS_PER_SEC)
using namespace std;
template <typename t1, typename t2> bool maximize(t1 &a, const t2 &b){if(a < b){a = b; return 1;} else return 0;};
template <typename t1, typename t2> bool minimize(t1 &a, const t2 &b){if(a > b){a = b; return 1;} else return 0;};
void load(){
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
// if(fopen("test.inp", "r")){
// freopen("test.inp", "r", stdin);
// freopen("test.out", "w", stdout);
// }
}
const int oo = 1e9 + 7;
const ll OO = 1e18 + 7;
const int maxn = 5e5 + 5;
int n;
int a[2 * maxn];
int pref[2 * maxn];
struct pp{
int val, id;
};
deque<pp> dq;
int k;
int res = 0;
void enter(){
cin >> n;
for(int i = 1; i <= n; i++){
cin >> a[i];
a[i + n] = a[i];
}
pref[0] = 0;
for(int i = 1; i <= n * 2; i++){
pref[i] = pref[i - 1] + a[i];
}
}
int get_range(int l, int r){
return pref[r] - pref[l - 1];
}
void add(int val, int id){
while(!dq.empty() && dq.back().val > val) dq.pop_back();
dq.push_back({val, id});
}
void Try(){
k = (n + 1) / 2;
for(int i = 1; i <= k; i++){
add(get_range(i, i + k - 1), i);
}
for(int i = k; i <= n + k - 1; i++){
while(dq.front().id <= i - k) dq.pop_front();
maximize(res, dq.front().val);
add(get_range(i + 1, i + k), i);
// cout << i << ' ' << res << ' ' << dq.front().id << ' ' << dq.back().id << ' ' << dq.back().val << '\n';
}
cout << res;
}
signed main(){
load();
enter();
Try();
cerr << '\n' << "Time ran: " << TIME << "s\n";
}
