#include <cstdio>
#include <stdio.h>
#include <stdbool.h>
#include <iostream>
#include <map>
#include <vector>
#include <climits>
#include <stack>
#include <string>
#include <queue>
#include <algorithm>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cmath>
#include <cctype>
#include <bitset>
#include <iomanip>
#include <cstring>
#include <numeric>
#include <cassert>
#include <chrono>
using namespace std;
#define int long long
#define pii pair<int, int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
int n;
vector<int> vect;
bool check(int mid){
for (int i=1; i<=n; ++i){
int id=lower_bound(vect.begin(), vect.end(), vect[i-1]+mid)-vect.begin()+1;
if (id>=i+n)continue;
id=lower_bound(vect.begin(), vect.end(), vect[id-1]+mid)-vect.begin()+1;
if (id>=i+n)continue;
id=lower_bound(vect.begin(), vect.end(), vect[id-1]+mid)-vect.begin();
if (id>=i+n)continue;
return 1;
}
return 0;
}
int32_t main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n;
vect.resize(2*n+1, 0);
for (int i=1; i<=n; ++i)cin>>vect[i], vect[i+n]=vect[i];
for (int i=1; i<=2*n; ++i)vect[i]+=vect[i-1];
int low=0, high=LLONG_MAX/2;
while (low+1<high){
int mid=(low+high)/2;
if (check(mid))low=mid;
else high=mid;
}
cout<<low;
}
