#include <iostream>
using namespace std;
const int N = 5e5 + 10;
const int INF = 1e9;
struct ST {
int st[N << 2];
ST () {fill_n(st, N << 2, INF);}
void update(int l, int r, int u, int v, int val, int id) {
if (l > v || r < u) return;
if (l >= u && r <= v) {
st[id] = min(st[id], val);
return;
}
int m = (l + r) >> 1;
update(l, m, u, v, val, id << 1);
update(m + 1, r, u, v, val, id << 1 | 1);
}
int get(int l, int r, int u, int id) {
if (l == r) return st[id];
int m = (l + r) >> 1;
if (u <= m) return min(st[id], get(l, m, u, id << 1));
return min(st[id], get(m + 1, r, u, id << 1 | 1));
}
} seg;
int n, a[N];
int get(int l, int r) {
if (r > n) return get(l, n) + get(1, r - n);
return a[r] - a[l - 1];
}
int main() {
if (fopen("chonso.inp", "r")) {
freopen("chonso.inp", "r", stdin);
freopen("chonso.out", "w", stdout);
}
cin.tie(nullptr);
cout.tie(nullptr);
ios_base::sync_with_stdio(false);
cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> a[i];
a[i] += a[i - 1];
}
int len = (n >> 1) + (n & 1);
for (int i = 1; i <= n; ++i) {
int r = i + len - 1, val = get(i, i + len - 1);
if (r > n) {
seg.update(1, n, i, n, val, 1);
seg.update(1, n, 1, r - n, val, 1);
} else {
seg.update(1, n, i, r, val, 1);
}
}
int ans = 0;
for (int i = 1; i <= n; ++i) ans = max(ans, seg.get(1, n, i, 1));
cout << ans << "\n";
return 0;
}
