/* In the name of God, aka Allah */
// let this be mytemp.cpp
#include<bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define endl '\n'
#define mk make_pair
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int N = 5e5 + 50, LG = 20;
int n, a[N], sum, s[N], sp[LG][N];
int get(int l, int r) {
int k = 31-__builtin_clz(r-l+1);
return max(sp[k][l], sp[k][r-(1<<k)+1]);
}
void solve() {
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> a[i];
sum += a[i];
}
for (int i = 1; i <= 2*n; i++) {
s[(i-1)%n+1] = s[(i-2)%n+1] + a[(i-1)%n+1];
if (i > n/2) s[(i-1)%n+1] -= a[(i-n/2-1)%n+1];
}
for (int i = 1; i <= n; i++) {
sp[0][i] = s[i];
}
for (int k = 1; k < LG; k++) {
for (int i = 1; i <= (n-(1<<k)+1); i++) {
sp[k][i] = max(sp[k-1][i], sp[k-1][i+(1<<(k-1))]);
}
}
int ans = 0;
for (int i = 1; i <= n; i++) {
if (i + n/2 > n) {
ans = max(ans, sum-get((i+(n/2)-1)%n+1, i-1));
}
else {
ans = max(ans, sum-max((i > 1? get(1, i-1):0), get(i+(n/2), n)));
}
}
cout << ans << endl;
}
int main() {
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
solve();
return 0;
}
