#ifdef DEBUG
#include"bits/dbg.h"
#else
#define dbg(...)
#endif

#include"bits/stdc++.h"
#define int long long
#define P pair<int,int>
#define x first
#define y second
using namespace std;

const int maxn = 1e6+5;
int s[maxn];
int n;

bool check (int mid) {
    dbg(mid);
    vector<P> v; //{ans, size}
    for (int i=1;i<=n+n;i++) {
        if (v.size() && (v.back().first <= mid || v.back().second > 1) && v.back().first+mid >= s[i]) {
            P p = {v.back().first+s[i], v.back().second+1};
            v.pop_back();
            v.push_back(p);
        }
        else {
            v.push_back({s[i], 1});
        }
        if (!(v.back().first <= mid || v.back().second > 1)) continue;
        int sum = v.back().first;
        int sz = v.back().second;
        v.pop_back();
        if (v.size() && v.back().first <= sum+mid) {
            while (v.size() && v.back().first <= sum+mid) {
                sum += v.back().first;
                sz += v.back().second;
                v.pop_back();
            }       
        }
        v.push_back({sum, sz});     
    }
    for (auto e : v) {
        if (e.second >= n) return true;
    }
    return false;
}
signed main () {
    cin >> n;
    for (int i=1;i<=n;i++) {
        cin >> s[i];
        s[n+i] = s[i];
    }
    int l = 0;
    int r = 1e13;
    int ans = -1;
    while (l <= r) {
        int mid = (l+r)/2;
        if (check(mid)) {
            r = mid-1;
            ans = mid;
        }
        else {
            l = mid+1;
        }
    }
    dbg(check(2));
    dbg(check(4));
    dbg(check(12));
    cout << ans << endl;

}