#include <bits/stdc++.h>
using namespace std;
#define int int64_t
#define pb push_back
#define emb emplace_back
#define fr first
#define sc second
#define all(x) x.begin(),x.end()
#define sp << " " <<
#define N 100000
#define inf (int)1e14
typedef pair<int,int> ii;
typedef tuple<int,int,int> iii;
int n,sum=0,a[2*N];
bool calc(int x){
int i1=0,i2=0,i3=0;
int sum1=0,sum2=0;
while(i1<n){
while(i2<i1+n && sum1<x){
sum1+=a[i2];
sum2-=a[i2];
i2++;
}
while(i3<i1+n && sum2<x){
sum2+=a[i3];
i3++;
}
if(sum1>=x && sum2>=x && sum-sum1-sum2>=x)
return true;
sum1-=a[i1];
i1++;
}
return false;
}
void solve(){
cin >> n;
for(int i=0;i<n;i++){
cin >> a[i];
a[n+i]=a[i];
sum+=a[i];
}
int l=1,r=sum/3;
while(l<r){
int mid=(l+r+1)/2;
if(calc(mid)) l=mid;
else r=mid-1;
}
cout << l << endl;
}
int32_t main(){
//~ freopen("hopscotch.in","r",stdin);
//~ freopen("hopscotch.out","w",stdout);
cout << fixed << setprecision(0);
ios_base::sync_with_stdio(false);
cin.tie(NULL);cout.tie(NULL);
int test=1;
//~ cin >> test;
while(test--) solve();
}
