//package ojuz;
import java.io.*;
import java.util.*;
public class hac {
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int n = Integer.parseInt(reader.readLine());
int moves = (n + 1) / 2;
int[] arr = new int[n + moves - 1];
String[] read = reader.readLine().split(" ");
for (int i = 0; i < n; i++) arr[i] = Integer.parseInt(read[i]);
for (int i = n; i < arr.length; i++) arr[i] = arr[i - n];
int val = 0;
for (int i = 0; i < moves; i++) val += arr[i];
int[] pref = new int[n + moves - 1];
for (int i = 0; i < n - 1; i++) {
pref[i] = val;
val -= arr[i];
val += arr[i + moves];
}
pref[n - 1] = val;
for (int i = n; i < pref.length; i++) pref[i] = pref[i - n];
Deque<Integer> deque = new ArrayDeque<>();
for (int i = 0; i < moves; i++) {
while (!deque.isEmpty() && pref[deque.getLast()] >= pref[i]) deque.pollLast();
deque.addLast(i);
}
int best = pref[deque.getFirst()];
for (int i = moves; i < pref.length; i++) {
while (!deque.isEmpty() && pref[deque.getLast()] >= pref[i]) deque.pollLast();
deque.addLast(i);
if (deque.getFirst() < (i - moves)) deque.pollFirst();
best = Math.max(best, pref[deque.getFirst()]);
}
System.out.println(best);
}
}
