#include "bits/stdc++.h"
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
using str = string;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;
using vi = vector<int>;
using vvi = vector<vi>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<db>;
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vpd = vector<pd>;
#define mp make_pair
#define f first
#define s second
// const int MOD = 1e9 + 7;
// const int MX = 2e5 + 5;
const int INF = 1e9;
// const ll INF = 1e18; // not too close to LLONG_MAX
// const ld PI = acos((ld)-1);
// const int dx[4] = {1, 0, -1, 0},
// dy[4] = {0, 1, 0, -1}; // for every grid problem!!
#define sz(x) int(x.size())
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define rall(x) x.rbegin(), x.rend()
#define sor(x) sort(all(x))
#define rsz resize
#define ins insert
#define ft front()
#define bk back()
#define pb push_back
#define eb emplace_back
#define pf push_front
#define lb lower_bound
#define ub upper_bound
#define endl "\n"
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i, a) ROF(i, 0, a)
#define trav(a, x) for (auto &a : x)
template <class T> using pqg = priority_queue<T, vector<T>, greater<T>>;
constexpr int pct(int x) { return (int)__builtin_popcount(x); }
constexpr int bits(int x) {
return x == 0 ? 0 : 31 - (int)__builtin_clz(x);
}
template <typename T, typename... U>
void dbgh(const T& t, const U&... u) {
cerr << t;
((cerr << " | " << u), ...);
cerr << endl;
}
void setPrec() { cout << fixed << setprecision(15); }
void unsyncIO() { cin.tie(0)->sync_with_stdio(0); }
void setIn(str s) { freopen(s.c_str(), "r", stdin); }
void setOut(str s) { freopen(s.c_str(), "w", stdout); }
void setIO(str s = "") {
unsyncIO();
setPrec();
cin.exceptions(cin.failbit);
if (sz(s)) setIn(s + ".in"), setOut(s + ".out");
}
#ifdef LOCAL
const int L = 100;
#define dbg(...) \
cerr << "L" << __LINE__ << " [" << #__VA_ARGS__ << "]" \
<< ": "; \
dbgh(__VA_ARGS__)
#else
const int L = 500000;
#define dbg(...)
#endif
int nums[L];
void solve() {
int n; cin >> n;
F0R(i,n) cin >> nums[i];
int ct = (n+1)/2;
int ans = -1*INF;
deque<int> myQ;
// ind starts at 0
int sum = 0;
FOR(ind,n-ct,n) sum += nums[ind%n];
FOR(ind,n-ct,n) {
sum += nums[(ind+ct)%n];
sum -= nums[ind];
while (myQ.size()) {
if (myQ.back()>sum) myQ.pop_back();
else break;
}
myQ.push_back(sum);
}
int total = 0;
F0R(ind,n) total += nums[ind];
F0R(ind,n) {
ans = max(ans,myQ.front());
sum += nums[(ind+ct)%n];
sum -= nums[ind];
while (myQ.size()) {
if (myQ.back()>sum) myQ.pop_back();
else break;
}
myQ.push_back(sum);
int removed = total-sum;
if (n%2) {
removed += nums[(ind+ct)%n];
}
if (myQ.front()==removed) myQ.pop_front();
}
cout << ans;
}
int main() {
#ifdef LOCAL // call with -DLOCAL
freopen("../input.txt", "r", stdin);
freopen("../myoutput.txt", "w", stdout);
freopen("../debug.txt", "w", stderr);
#else
setIO();
#endif
solve();
}
