#include <bits/stdc++.h>
#define st first
#define nd second
using lint = int64_t;
constexpr int mod = int(1e9) + 7;
constexpr int inf = 0x3f3f3f3f;
constexpr int ninf = 0xcfcfcfcf;
constexpr lint linf = 0x3f3f3f3f3f3f3f3f;
const long double pi = acosl(-1.0);
// Returns -1 if a < b, 0 if a = b and 1 if a > b.
int cmp_double(double a, double b = 0, double eps = 1e-9) {
return a + eps > b ? b + eps > a ? 0 : 1 : -1;
}
using namespace std;
template<typename T, T (*op)(const T&, const T&)> struct monotonic_queue {
vector<T> as, aas;
vector<T> bs, bbs;
void reserve(int N) {
as.reserve(N); aas.reserve(N);
bs.reserve(N); bbs.reserve(N);
}
void reduce() {
while (!bs.empty()) {
as.push_back(bs.back());
aas.push_back(aas.empty() ? bs.back() : op(bs.back(), aas.back()));
bs.pop_back(); bbs.pop_back();
}
}
T get() {
if (as.empty()) reduce();
return (bbs.empty() ? aas.back() : op(aas.back(), bbs.back()));
}
bool empty() const { return (as.empty() && bs.empty()); }
int size() const { return int(as.size()) + int(bs.size()); }
T front() {
if (as.empty()) reduce();
return as.back();
}
void push(const T& val) {
bs.push_back(val);
bbs.push_back(bbs.empty() ? val : op(bbs.back(), val));
}
void pop() {
if (as.empty()) reduce();
as.pop_back();
aas.pop_back();
}
};
// min/max
template<typename T> T mapping_max(const T& a, const T& b) {
return max(a, b);
}
template<typename T> using max_monotonic_queue = monotonic_queue<T, mapping_max>;
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
int n;
cin>>n;
vector<lint>v(n+n), pref(n+n+1);
for(int i=0;i<n;i++) cin>>v[i], v[i+n] = v[i];
for(int i=1;i<=n+n;i++){
pref[i] = pref[i-1] + v[i-1];
}
max_monotonic_queue<lint>q;
for(int i=1;i+n/2<=n;i++){
q.push(pref[i+n/2-1] - pref[i-1]);
}
lint ans = linf;
for(int i=0;i<n;i++){
ans = min(ans, q.get());
q.pop();
q.push(pref[n+i] - pref[n+i-n/2]);
}
cout<<pref[n] - ans<<"\n";
return 0;
}
/*
[ ]Leu o problema certo???
[ ]Ver se precisa de long long
[ ]Viu o limite dos fors (é n? é m?)
[ ]Tamanho do vetor, será que é 2e5 em vez de 1e5??
[ ]Testar sample
[ ]Testar casos de borda
[ ]1LL no 1LL << i
[ ]Testar mod (é 1e9+7, mesmo?, será que o mod não ficou negativo?)
*/
