#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define N 4000005
#define ff first
#define ss second
#define pb push_back
#define sz(s) (int)s.size()
#define rep(c, a, b) for(c = a; c <= b; c++)
ll n, v[N], mx, sum, answer, k, l;
multiset <ll> s;
deque <ll> d;
int main () {
ios::sync_with_stdio(0);cin.tie(0);
cin >> n;
k = (n+1)/2;
for(int i = 1; i <= n; i++) {
cin >> v[i];
if(i <= k) sum += v[i];
}
for(int i = 1; i <= n; i++) {
v[i + n] = v[i];
}
l = 1;
s.insert(sum);
d.pb(sum);
for(int i = k + 1; i <= 2*n; i++) {
sum -= v[l];
sum += v[i];
d.pb(sum);
s.insert(sum);
if(sz(s) == k) {
mx = max(mx,(*s.begin()));
s.erase(s.find(d[0]));
d.pop_front();
}
l++;
}
cout << mx << '\n';
}
