#include <iostream>
#include <cstdio>
#include <algorithm>
#include <stack>
using namespace std;
#define endl '\n'
#define ll long long
#define pi pair<ll, ll>
#define f first
#define s second
struct mque{
stack<pi> s1, s2;
ll mn(stack<pi> &s){
return s.empty() ? 0x3f3f3f3f3f3f3f3f : s.top().s;
}
void add(ll x){
s1.push({x, min(x, mn(s1))});
}
void del(){
if(s2.empty()) for(; !s1.empty(); s1.pop()) s2.push({s1.top().f, min(s1.top().f, mn(s2))});
s2.pop();
}
ll qry(){
return min(mn(s1), mn(s2));
}
};
const int mxn = 1500001;
int n;
ll a[mxn];
mque q;
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n;
for(int i = 1; i <= n; i++){
cin >> a[i];
for(int j = 1; j < 3; j++) a[j * n + i] = a[i];
a[i] += a[i - 1];
}
ll ret = 0;
for(int i = n + 1; i <= 3 * n; i++){
a[i] += a[i - 1];
q.add(a[i] - a[i - (n + 1) / 2]);
if(i - n > (n + 1) / 2) q.del(), ret = max(ret, q.qry());
}
cout << ret << endl;
return 0;
}
