#include<bits/stdc++.h>
using namespace std;
const int mxN = 2*5e5+5;
int pref[mxN], a[mxN], sig[mxN], n, k;
int rs(int i, int j) {
if(i <= j) return pref[j] - pref[i-1];
return rs(i, n) + rs(1, j);
}
signed main() {
//freopen("hac.in", "r", stdin);
//freopen("hac.out", "w", stdout);
cin >> n;
k = (n + 1) / 2;
for(int i = 1; i <= n; i++) cin >> a[i];
for(int i = 1; i <= n; i++) pref[i] = a[i] + pref[i-1];
for(int i = 1; i <= n; i++) {
if(i+k-1 <= n) sig[i] = rs(i, i+k-1);
else sig[i] = rs(i, i+k-1-n);
}
for(int i = 1; i <= n; i++) sig[i+n] = sig[i];
//for(int i = 1; i <= 2*n; i++) cerr << sig[i] << '\n';
deque<int> st;
int res = INT_MIN;
for(int i = 1; i <= 2*n; i++) {
while(st.size() and sig[i] <= sig[st.back()]) st.pop_back();
st.push_back(i);
while(st.size() and st.front() + k - 1 < i) st.pop_front();
if(st.size() && i >= k) res = max(res, sig[st.front()]);
}
cout << res << '\n';
}
