#include <iostream>

using namespace std;

int main(){
    int n;
    cin >> n;
    int t, now;
    now = t = 0;
    int nxt;
    for(int i = 0; i < n; i ++ ){
        cin >> nxt;
        if(nxt == now)  t += 5;
        else if(nxt > now)  t += (nxt - now) * 6 + 5;
        else    t += (now - nxt) * 4 + 5;
        now = nxt;
    }
    cout << t << endl;
    return 0;
}