Elevator

import java.util.Scanner;

public class Main{
    public static void main(String args[]) {
        Scanner sc=new Scanner(System.in);
        while(true){
            int n=sc.nextInt();
            if(n==0) {
                break;
            }
            int current=0;
            int temp=0;
            int tsum=0;
            for(int i=0;i<n;i++) {
                int end=sc.nextInt();
                if(end>temp) {
                    tsum=tsum+(end-temp)*6+5;
                }
                else {
                    tsum=tsum+(temp-end)*4+5;
                }
                temp=end;
            }
            System.out.println(tsum);
        }
    }
}