#include <bits/stdc++.h>
using namespace std;
const int MAXN = 5e5+5;
int arr[MAXN],pref[MAXN];
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int N; cin >> N;
for(int i = 1;i<=N;++i){
cin >> arr[i];
pref[i] = pref[i-1]+arr[i];
}
int len = (N+1)/2, ans = 0;
for(int i = 1;i<=N;++i){
int curmin = -1;
if(i+len-1 <= N){
curmin = pref[i+len-1]-pref[i-1];
}
else{
curmin = pref[N]-pref[i-1]+pref[len-(N-i+1)];
}
//cout << i << " " << curmin << " ";
if(i-len >= 0){
curmin = min(curmin,pref[i]-pref[i-len]);
//cout << pref[i]-pref[i-len] << "\n";
}
else{
curmin = min(curmin,pref[i]+pref[N]-pref[N-(len-i)]);
//cout << pref[i]+pref[N]-pref[N-(len-i)] << "\n";
}
ans = max(ans,curmin);
}
cout << ans << "\n";
return 0;
}
