#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define ll long long
#define mp(x, y) make_pair(x, y)
#define sz(v) ((int) (v).size())
#define all(v) (v).begin(), (v).end()
#define MASK(i) (1LL << (i))
#define BIT(x, y) (((x) >> (y)) & 1)
#define pb push_back
#define max_rng *max_element
#define min_rng *min_element
#define rep(i, n) for(int i = 1, _n = (n); i <= _n; ++i)
#define forn(i, a, b) for(int i = (a), _b = (b); i <= _b; ++i)
#define ford(i, a, b) for(int i = (a), _b = (b); i >= _b; --i)
template <class X, class Y>
inline bool maximize(X &x, Y y) {
return (x < y ? x = y, true : false);
}
template <class X, class Y>
inline bool minimize(X &x, Y y) {
return (x > y ? x = y, true : false);
}
template <class X>
inline void compress(vector<X> &a) {
sort(all(a));
a.resize(unique(all(a)) - a.begin());
}
int ctz(ll x) { return __builtin_ctzll(x); }
int lg(ll x) { return 63 - __builtin_clzll(x); }
int popcount(ll x) { return __builtin_popcount(x); }
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rand(ll l, ll r) {
return l + abs((ll) rng()) % (r - l + 1);
}
const ll oo = (ll) 1e17;
const int inf = (ll) 2e9 + 7, mod = (ll) 1e9 + 7;
const int mxn = 2e6, mxm = 3e6;
const int LG = 18;
int n;
int a[mxn + 5];
int pref[mxn + 5], p[mxn + 5];
int main(void) {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n;
rep(i, n) {
cin >> a[i];
a[i + n] = a[i];
}
int v = n / 2 + (n & 1);
rep(i, n << 1) {
pref[i] = pref[i-1] + a[i];
p[i] = pref[i] - (i < v ? 0 : pref[i - v]);
}
int ans = 0;
deque<int> dq;
ford(i, n << 1, 1) {
while (!dq.empty() && p[i] < p[dq.front()])
dq.pop_front();
dq.push_front(i);
while (dq.back() - i >= v)
dq.pop_back();
if (i + v - 1 <= (n << 1))
maximize(ans, p[dq.back()]);
}
cout << ans;
return 0;
}
