#include <bits/stdc++.h>
#define lsb(x) (x & (-x))
#define ll long long
#define ull unsigned long long
#define ld long double
// 217
// 44
using namespace std;
const int MAXN = (int) 5e5 + 5;
int arr[MAXN + 1], n;
int pref[MAXN + 1], suff[MAXN + 1];
inline int get(int l, int r) {
if(l <= 0) {
return suff[n + l] + pref[r];
}
if(r > n) {
return suff[l] + pref[r - n];
}
return pref[r] - pref[l - 1];
}
inline int get(multiset <int> &mst, int x) {
if(mst.count(x) > 1) {
return x;
}
return *prev(mst.find(x));
}
int main() {
//ifstream cin("A.in");
//ofstream cout("A.out");
int i;
ios::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
cin >> n;
for(i = 1; i <= n; i++) {
cin >> arr[i];
pref[i] = pref[i - 1] + arr[i];
}
for(i = n; i >= 1; i--) {
suff[i] = suff[i + 1] + arr[i];
}
multiset <int> mst;
int len = (n + 1) / 2;
for(i = 1; i <= len; i++) {
mst.insert(get(i - len + 1, i));
}
int ans = *mst.begin();
for(i = 2; i <= n; i++) {
mst.erase(mst.find(get(i - 1 - len + 1, i - 1)));
mst.insert(get(i, i + len - 1));
ans = max(ans, *mst.begin());
}
cout << ans;
//cin.close();
//cout.close();
return 0;
}
