#ifdef DEBUG
#define _GLIBCXX_DEBUG
#endif
//#pragma GCC optimize("O3")
#include<bits/stdc++.h>
using namespace std;

#define pb push_back

typedef long long ll;
typedef long double ld;


ll get(vector<int> a)
{
    ll A = 0;
    while (true)
    {
        if (a[0]==0) return A+1;
        if (a[0]==1)
        {
            vector<int> b(a.size()-1);
            for (int i=0;i<b.size();i++)
            {
                if (a[i+1]==0) b[i] = 0;
                else b[i] = a[i+1]-1;
            }
            return A+get(b)*2;
        }
        int x = a[0];
        for (int j=0;j<x;j++) swap(a[j],a[j+1]);
        A++;
    }
    assert(false);
    return -1;
}

void solve()
{
    int n = 32;
    cin >> n;
    vector<int> a(n);
    for (int i=0;i<n;i++)
    {
        a[i] = i;
        cin >> a[i];
    }
    //mt19937 gen(time(0));
    //shuffle(a.begin(),a.end(),gen);
    ll A = get(a);
    cout << A-1 << "\n";
    return;
    ll A2 = A-1;
    A = 0;
    while (a[0]!=0)
    {
        int x = a[0];
        for (int j=0;j<x;j++) swap(a[j],a[j+1]);
        A++;
    }
    //cout << A << "\n";
    assert(A==A2);
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
//#ifdef DEBUG
//    freopen("input.txt", "r", stdin);
//#endif
    int T = 1;
    while (T--) solve();
    return 0;
}