HDOJ1008

import java.util.Scanner;
public class Main {
    public static void main(String[] args)
    {
        Scanner scanner=new Scanner(System.in);
        while(true)
        {
            short N=scanner.nextShort();
            if(N==0)
                break;
            short s1=0;
            short s2=0;
            int sum=0;
            for(short i=0;i<N;i++)
            {
                s2=scanner.nextShort();
                if(s2>=s1)
                {
                    sum+=(s2-s1)*6+5;
                }
                else 
                {
                    sum+=(s1-s2)*4+5;
                }
                s1=s2;
            }
            System.out.println(sum);
        }
    }
}