#include<bits/stdc++.h>
using namespace std;
struct maxqueue {
queue<int> q;
deque<int> dq;
void pop() {
int v=q.front();
if (v==dq.front()) dq.pop_front();
q.pop();
}
void push(int v) {
q.push(v);
while (!dq.empty() && dq.back()<v) dq.pop_back();
dq.push_back(v);
}
int query() {
return dq.front();
}
};
int main() {
cin.tie(0)->sync_with_stdio(false);
int n, c=0, t=0;
cin >> n;
vector<int> v(n), s(n);
for (int i = 0; i < n; ++i) {
cin >> v[i];
if (i<n/2) c+=v[i];
t+=v[i];
}
maxqueue mq;
for (int i = 0; i < n; ++i) {
s[i]=c;
if (i>0 && i<(n+1)/2+1) mq.push(s[i]);
c+=v[(i+n/2)%n]-v[i];
}
int m=0;
for (int i = 0; i < n; ++i) {
m=max(m, t-mq.query());
mq.pop();
mq.push(s[(i+(n+1)/2+1)%n]);
} cout << m << '\n';
return 0;
}
