#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define sz size()
#define ff first
#define ss second
#define pb push_back
#define pii pair <int, int>
#define dur exit(0)
#define dur1 return(0)
const int NN = 1e6 + 5;
ll n, p[NN], a[NN], sum, st[NN * 4];
void update (int idx, int x, int y, int l, ll r) {
if (x == y) {
st[idx] = r;
return;
}
int mid = (x + y) / 2;
if (l <= mid)
update (idx * 2, x, mid, l, r);
else
update (idx * 2 + 1, mid + 1, y, l, r);
st[idx] = max (st[idx * 2], st[idx * 2 + 1]);
}
void jogap (int idx, int x, int y, int l, int r) {
if (l <= x and y <= r) {
sum = max (st[idx], sum);
return;
}
if (l > y or x > r) return;
int mid = (x + y) / 2;
jogap (idx * 2, x, mid, l, r);
jogap (idx * 2 + 1, mid + 1, y, l, r);
}
int main () {
// freopen ("input.txt", "r", stdin);
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> a[i];
a[i + n] = a[i];
}
for (int i = 1; i <= 2 * n; ++i) {
p[i] = p[i - 1] + a[i];
}
int ope = n / 2;
for (int i = 1; i <= 2 * n; ++i) {
if (i + ope - 1 > 2 * n) break;
update (1, 1, 2 * n, i, p[i + ope - 1] - p[i - 1]);
}
ll mx = 0, jog = 0;
for (int i = 1; i <= n; ++i) {
ll jog = 0;
sum = 0;
jogap (1, 1, 2 * n, i + 1, (n + i - 1) - ope + 1);
jog = max (jog, sum);
mx = max (mx, p[n] - jog);
}
cout << mx;
}
