#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define repr(i,n) for(int i = (int)(n); i >= 0; i--)
#define all(v) v.begin(),v.end()
typedef long long ll;

int main(){
    int N;
    cin >> N;
    vector<int> vec(N);
    rep(i,N){
        cin >> vec[i];
    }
    vector<pair<int,int> > minimum_sort(N);
    rep(i,N){
        minimum_sort[i].first = vec[i];
        minimum_sort[i].second = i;
    }
    sort(all(minimum_sort));
    int ans;
    if (minimum_sort[0].second < minimum_sort[1].second){
        int fin_num = N;
        for (int i = 2; i < N; i++){
            if (minimum_sort[i].second < minimum_sort[i - 1].second){
                fin_num = i;
                break;
            }
        }
        if (fin_num == N){
            ans = -1;
        }
        else if (minimum_sort[fin_num].second < minimum_sort[0].second){
            ans = minimum_sort[fin_num].first + minimum_sort[0].first + minimum_sort[1].first;
        }
        else{
            rep(i,fin_num){
                if (minimum_sort[fin_num].second < minimum_sort[i].second){
                    ans = minimum_sort[fin_num].first + minimum_sort[0].first + minimum_sort[i].first;
                    break;
                }
            }
        }
    }
    if (minimum_sort[0].second > minimum_sort[1].second){
        int fin_num = N;
        for (int i = 2; i < N; i++){
            if (minimum_sort[i].second > minimum_sort[i - 1].second){
                fin_num = i;
                break;
            }
        }
        if (fin_num == N){
            ans = -1;
        }
        else if (minimum_sort[fin_num].second > minimum_sort[0].second){
            ans = minimum_sort[fin_num].first + minimum_sort[0].first + minimum_sort[1].first;
        }
        else{
            rep(i,fin_num){
                if (minimum_sort[fin_num].second > minimum_sort[i].second){
                    ans = minimum_sort[fin_num].first + minimum_sort[0].first + minimum_sort[i].first;
                }
                break;
            }
        }
    }
    cout << ans << endl;
}