//简单循环
//不用忘记更新cur
#include<iostream>

using namespace std;


int main()
{
    int n;
    cin>>n;
    int last=0;
    int res=0;
    while(n--)
    {
        int cur;
        cin>>cur;
        if(last<cur) res+=(cur-last)*6+5;
        else res+=(last-cur)*4+5;

        last=cur; 
    }
    cout<<res<<endl;
    return 0;
}