#include <bits/stdc++.h>
using namespace std;
#define f first
#define s second
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define LSB(x) ((x) & -(x))
#define sz(x) (int)(x.size())
#define uid(a, b) uniform_int_distribution<int>(a, b)(rng)
#define __lcm(a, b) ((a) * (b)) / __gcd(a, b)
template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ", "; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? ", " : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef DEBUG
#define dbg(x...) cerr << "\e[DEBUG] "<<__func__<<": "<<__LINE__<<", [" << #x << "] = ["; _print(x);
#else
#define dbg(x...)
#endif
struct Data {
int r1, c1, r2, c2, d;
Data(int _r1, int _c1, int _r2, int _c2, int _d) : r1(_r1), c1(_c1), r2(_r2), c2(_c2), d(_d) {};
bool operator== (const Data& b) const {
return r1 == b.r1 && r2 == b.r2 && c1 == b.c1 && c2 == b.c2 && d == b.d;
}
};
struct custom_hash {
static uint64_t splitmix64(uint64_t x) {
// http://xorshift.di.unimi.it/splitmix64.c
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
size_t operator()(string x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
uint64_t res = 0;
for (int i = 0; i < sz(x); i++){
res ^= x[i] + FIXED_RANDOM;
res = splitmix64(res);
}
return res;
}
size_t operator()(Data x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
uint64_t res = ((splitmix64(x.r1) ^ splitmix64(splitmix64(x.c1) + FIXED_RANDOM)) ^ splitmix64(splitmix64(x.r2) ^ (splitmix64(splitmix64(x.c2)) ^ x.d))) + FIXED_RANDOM;
return res;
}
};
const ll MOD = 998244353;
const ll INFLL = 1e18 + 5;
const int INF = 1e9 + 5;
char nl = '\n';
ll modPow(ll n, ll k){
if (k == 0) return 1;
ll res = modPow(n, k / 2);
res = res * res % MOD;
if (k & 1) return res * n % MOD;
return res;
}
bool ccw(pair<ll, ll> p1, pair<ll, ll> p2, pair<ll, ll> p3){
ll val = (p1.f * p2.s - p1.s * p2.f + p2.f * p3.s - p2.s * p3.f + p3.f * p1.s - p3.s * p1.f);
if (val <= 0) return 1;
return 0;
}
const int mxN = 1e5+5;
void TestCase(){
int n; cin >> n;
vector<int> v(2*n);
int tot = 0;
for (int i = 0; i < n; i++) {
cin >> v[i];
tot += v[i];
v[i + n] = v[i];
}
int h = (n+1)/2, o = n - h;
vector<int> pref(2*n); pref[0] = v[0];
for (int i = 0; i < 2*n; i++) pref[i] = (i > 0 ? pref[i-1] : 0) + v[i];
vector<int> sum(2*n);
deque<pair<int, int>> dq;
for (int i = 0; i + o - 1 < 2*n; i++){
sum[i] = pref[i + o - 1] - ((i > 0) ? pref[i-1] : 0);
if (i > 0 && i + o - 1 < n){
while (!dq.empty() && dq.back().s <= sum[i]) dq.pop_back();
dq.push_back({i, sum[i]});
}
}
int ans = -1;
for (int i = 0; i < n; i++){
ckmax(ans, tot - dq.front().s);
if (!dq.empty() && dq.front().f == i+1) dq.pop_front();
pair<int, int> cur = {i+n-o+1, sum[i+n-o+1]};
while (!dq.empty() && dq.back().s <= cur.s) dq.pop_back();
dq.push_back(cur);
}
cout << ans << nl;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int T = 1;
// cin >> T;
while (T--){
TestCase();
}
return 0;
}
