#include<bits/stdc++.h>
using namespace std;
#define nl "\n"
#define fi first
#define se second
#define pb push_back
#define ll long long
#define ull unsigned ll
#define RV  return void
#define sz(x) int(x.size())
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define fixed(n) fixed << setprecision(n)
#define cin(v) for (auto&i:v) cin >> i;
#define cout(v) for (auto&i:v) cout << i << " ";
#define clr(memo, x) memset(memo, x, sizeof memo)
#define FastCode ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

void  Zainab(){
            // #ifndef ONLINE_JUDGE
              freopen("hobz.in", "r", stdin);
              // freopen("longpath.out", "w", stdout);
            // #endif
}


ll n;
vector < ll > v ,dp;

const ll inf = 1e15;

ll rec(ll idx ) {

    if(idx >= n) return (idx == n ? 0 : inf);

    ll & ret = dp[idx];
    if(~ret)
        return ret ;
    ret =inf;

    for(ll i =1 ; i <= min( 7ll , n-idx ) ; ++i){

        ret = min(ret , 1ll * v[idx] * i  + rec(idx+i));
    }

    return ret;
}

void myCode( int test){

cin >> n;
v.assign(n,0);
cin(v);

dp.assign(n+1 , -1);

cout << rec(0) << nl;
// for(int i =0 ; i < n ; i++) cout << i << " " << dp[i] << nl;

}


int main(){
                                   FastCode ;

    int testCase=1;
        //  cin >> testCase ;
      for(int i=1 ; i<= testCase ; i++)
        myCode(i);

    return 0;
}