#include "bits/stdc++.h"
using namespace std;
#define forR(i, a) for(int i = 0; (i) < (a); ++(i))
#define REP(i, a, b) for(int i = (a); (i) < (b); ++i)
#define all(a) a.begin(), a.end()
#define boost() cin.sync_with_stdio(0); cin.tie(0)
#define printArr(arr) for(int asdfg : arr) cout << asdfg << ' '; cout << '\n'
#define open(x) freopen(((string) x + ".in").c_str(), "r", stdin); freopen(((string) x + ".out").c_str(), "w", stdout);
typedef long long ll;
struct pii{int a, b;};
const int MN = 2e6 + 10;
int v[MN], ra[MN];
signed main(){
int n; cin >> n;
int su = 0;
forR(i, n) {
cin >> v[i];
su += v[i];
}
forR(i, n) v[i + n] = v[i + 2 * n] = v[i];
int oSiz = n / 2;
for(int i=0, oWin=0; i < 3 * n; ++i){
oWin += v[i] - (i >= oSiz ? v[i-oSiz] : 0);
if(i >= oSiz - 1) ra[i - oSiz + 1] = oWin;
}
deque<pii> ma;
REP(i, 1, n-oSiz) {
while(!ma.empty() && ma.back().b < ra[i]) ma.pop_back();
ma.push_back({i, ra[i]});
}
int bes = 0;
forR(i, n){
int nex = i + n - oSiz;
while(!ma.empty() && ma.back().b < ra[nex]) ma.pop_back();
ma.push_back({nex, ra[nex]});
if(i >= ma.front().a) ma.pop_front();
bes = max(bes, su - ma.front().b);
}
cout << bes << '\n';
}
