#include <bits/stdc++.h>
using namespace std;
int main() {
int N;
cin >> N;
vector<int> A(2 * N);
for (int i = 0; i < N; i++) {
cin >> A[i];
A[i + N] = A[i];
}
int M = (N + 1) / 2;
vector<int> B(2 * N);
for (int i = 0; i < 2 * N; i++) {
if (i > 0) {
B[i] += B[i - 1];
}
B[i] += A[i];
if (i >= M) {
B[i] -= A[i - M];
}
}
int ans = 0;
deque<int> dq;
for (int i = 0; i <= 2 * N; i++) {
while (!dq.empty() && B[dq.back()] >= B[i]) {
dq.pop_back();
}
dq.push_back(i);
if (dq.front() + M <= i) {
dq.pop_front();
}
ans = max(ans, B[dq.front()]);
}
cout << ans << "\n";
}
