#include <iostream>
#include <vector>
#include "stdio.h"
using namespace std;
#define int long long
//
// Created by Otabek Jurabekov on 4/12/22.
//
template <typename Type> struct SegTree{
int Sz;
vector <Type> t, arr;
SegTree(int _n, Type _m){
t.assign((_n + 1) * 4 + 7, _m);
Sz = _n;
}
Type com(Type F, Type S){
return max(F, S);
}
void BuildTree(int v, int l, int r, vector <Type> &Array){
arr = Array; build(v, l, r);
}
void build(int v, int l, int r){
if(l == r){
t[v] = arr[l]; return;
}
int m = (l + r) >> 1;
build(v << 1, l, m); build(v << 1 | 1, m + 1, r);
t[v] = com(t[v << 1], t[v << 1 | 1]);
}
void upd_put_one(int v, int tl, int tr, int idx, Type del){
if(tl == tr){
t[v] = del; return;
}
int tm = (tl + tr) >> 1;
if(idx > tm) upd_put_one(v << 1 | 1, tm + 1, tr, idx, del);
else upd_put_one(v << 1, tl, tm, idx, del);
t[v] = com(t[v << 1], t[v << 1 | 1]);
}
void upd_add_one(int v, int tl, int tr, int idx, Type del){
if(tl == tr){
t[v] += del; return;
}
int tm = (tl + tr) >> 1;
if(idx > tm) upd_add_one(v << 1 | 1, tm + 1, tr, idx, del);
else upd_add_one(v << 1, tl, tm, idx, del);
t[v] = com(t[v << 1], t[v << 1 | 1]);
}
Type get_one(int v, int tl, int tr, int idx){
if(tl == tr){
return t[v];
}
int tm = (tl + tr) >> 1;
if(idx > tm) return t[v] + get_one(v << 1 | 1, tm + 1, tr, idx);
return t[v] + get_one(v << 1, tl, tm, idx);
}
Type get_lr(int v, int tl, int tr, int l, int r){
if(tl >= l && tr <= r) return t[v];
int tm = (tl + tr) >> 1;
if(tm < l) return get_lr(v << 1 | 1, tm + 1, tr, l, r);
if(tm >= r) return get_lr(v << 1, tl, tm, l, r);
return com(get_lr(v << 1, tl, tm, l, r), get_lr(v << 1 | 1, tm + 1, tr, l, r));
}
void upd_put_one(int idx, Type del){upd_put_one(1, 1, Sz, idx, del);}
void upd_add_one(int idx, Type del){upd_add_one(1, 1, Sz, idx, del);}
Type get_lr(int l, int r){return get_lr(1, 1, Sz, l, r);}
Type get_one(int idx){return get_one(1, 1, Sz, idx);}
};
signed main(){
ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#ifdef WTF
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
freopen("error.txt", "w", stderr);
#endif
int n; cin >> n;
vector <int> a(2 * n + 2);
for(int i = 1; i <= n; i ++){
cin >> a[i];
a[i + n] = a[i];
}
vector <int> pr(2 * n + 2, 0), sf(2 * n + 2, 0), P(2 * n + 2, 0), S(2 * n + 2, 0);
for(int i = 1; i <= n * 2; i ++){
pr[i] = pr[i - 1] + a[i];
P[i] = pr[i];
if(i - n / 2 >= 1) P[i] -= pr[i - n / 2];
}
for(int i = n * 2; i >= 1; i --){
sf[i] = sf[i + 1] + a[i];
S[i] = sf[i];
if(i + n / 2 <= 2 * n) S[i] -= sf[i + n / 2];
}
int K = n + n;
SegTree <int> SF(K, 0), PR(K, 0);
SF.BuildTree(1, 1, K, S);
PR.BuildTree(1, 1, K, P);
int ans = 0;
for(int i = 1; i <= n; i ++){
int mxs = n - (n / 2 - (i - 1)) + 1;
if(n / 2 - (i - 1) <= 0) mxs = n;
int mnp = (n / 2 - (n - i));
mnp = max(mnp, 1LL);
int cnt = 0;
if(mnp <= i - 1) cnt = PR.get_lr(1, 1, K, mnp, i - 1);
if(i + 1 <= mxs) cnt = max(cnt, SF.get_lr(1, 1, K, i + 1, mxs));
ans = max(ans, pr[n] - cnt);
}
cout << ans << "\n";
return 0;
}
