#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <numeric>
#include <functional>
using namespace std;
typedef long long int ll;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef map<ll, ll> mll_ll;
#define rep(i, a, b) for (ll i = a; i < b; i++)
ll N;
vll v;
vll dv;
ll get_slice(ll f, ll s) {
return dv[s + 1] - dv[f] + ((f > s) ? dv[N] : 0);
}
ll half_N;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> N;
half_N = (N + 1) / 2;
v.resize(N);
dv.resize(N + 1);
dv[0] = 0;
rep(i, 0, N) {
cin >> v[i];
dv[i + 1] = dv[i] + v[i];
}
ll best = 0;
mll_ll slices;
rep(i, 0, half_N) {
slices[get_slice(i, (i + half_N - 1) % N)]++;
}
rep(i, 0, N) {
best = max<ll>(best, slices.begin()->first);
slices[get_slice(i, (i + half_N - 1) % N)]--;
if (slices[get_slice(i, (i + half_N - 1) % N)] == 0) slices.erase(get_slice(i, (i + half_N - 1) % N));
slices[get_slice((i + half_N) % N, ((2 * half_N) + i - 1) % N)]++;
}
cout << best << endl;
return 0;
}
