import java.util.*;
public class Main {
    public static void main(String[] args) {

        Scanner input=new Scanner(System.in);
        while(input.hasNext()){

            int n=input.nextInt();  
            if(n==0)
            {
                break;
            }

            int arr[]=new int[n];
            int result=0;
            int side=0;
            for (int i=0;i<n;i++)
            {
                arr[i]=input.nextInt();

            }
            for (int i=0;i<n;i++)
            {
                if (arr[i]>side)
                {
                    result+=(arr[i]-side)*6+5;

                }
                else{
                    result+=(side-arr[i])*4+5;

                }
                side=arr[i];

            }
            System.out.println(result);
        }



    }
}