#include "bits/stdc++.h"
using namespace std;
#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif
const int maxn = 1e6 + 5;
const int LG = 20;
int n, a[maxn];
int lg2[maxn];
long long st[maxn][LG + 1];
long long pref[maxn];
long long get(int l, int r) {
int p = lg2[r - l + 1];
return min(st[l][p], st[r - (1 << p) + 1][p]);
}
void solve() {
cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> a[i];
a[i + n] = a[i];
}
int t = (n + 1) / 2;
for (int i = 1; i <= n << 1; ++i) {
pref[i] = pref[i - 1] + a[i];
st[i][0] = (i < t ? -1 : pref[i] - pref[i - t]);
}
for (int j = 1; j <= LG; ++j) {
for (int i = 1; i + (1 << j) <= (n << 1) + 1; ++i) {
st[i][j] = min(st[i][j - 1], st[i + (1 << (j - 1))][j - 1]);;
}
}
long long res = 0;
for (int i = t; i <= n * 2 - t + 1; ++i) {
res = max(res, get(i, i + t - 1));
}
cout << res;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
for (int i = 2; i < maxn; ++i) {
lg2[i] = lg2[i >> 1] + 1;
}
solve();
return 0;
}
