// #include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <vector>
#include <iomanip>
#include <string>
#include <queue>
#include <set>
#include <deque>
using namespace std;
#define endl "\n"
#define pb push_back
#define int long long
#define fi first
#define se second
const int N = 3e3 + 5, M = 1e9 + 7, LG = 20;
int n , A[N] , B[N] , C[N];
void solve(){
cin >> n;
for (int i=1 ; i<=n ; i++){
cin >> A[i];
}
int ans = 0;
for (int i=2 ; i<=n ; i++){
for (int k=1 ; k<=200 ; k++){
if (A[i] && A[i-1]){
B[i]++;
A[i]--;
A[i-1]--;
}
}
}
for (int i=3 ; i<=n ; i++){
for (int k=1 ; k<=200 ; k++){
if (A[i] && B[i-1]){
C[i]++;
A[i]--;
B[i-1]--;
}
}
}
for (int i=1 ; i<=n ; i++){
ans += A[i] * 3;
ans += B[i] * 5;
ans += C[i] * 7;
}
cout << ans << endl;
}
signed main(){
// freopen("" , "r" , stdin);
// freopen("" , "w" , stdout);
// cout << setprecision(30);
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int ts = 1;
// cin >> ts;
while(ts--){
solve();
}
}