#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define ar array
#define int long long
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
const int maxn = 1e6 + 5;
int a[maxn], sum[maxn], N;
signed main(void)
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#ifdef LOCAL
freopen("A.INP", "r", stdin);
freopen("A.OUT", "w", stdout);
#endif // LOCAL
int tot = 0;
cin >> N;
for(int i = 1; i <= N; ++i){
cin >> a[i];
a[i + N] = a[i];
tot += a[i];
}
for(int i = 1; i <= 2 * N; ++i){
sum[i] = sum[i - 1] + a[i];
}
deque<ii> dq;
int j;
for(int i = 1; i <= N - N / 2 + 1; ++i){
int v = sum[i + N / 2 - 1] - sum[i - 1];
while(dq.size() && dq.back().fi < v) dq.pop_back();
dq.eb(v, i);
j = i;
}
int res = 0;
for(int i = 1; i <= N; ++i){
while(dq.size() && dq.front().se == i) dq.pop_front();
res = max(res, tot - dq.front().fi);
++j;
int v = sum[j + N / 2 - 1] - sum[j - 1];
while(dq.size() && dq.back().fi < v) dq.pop_back();
dq.eb(v, j);
}
cout << res;
}
