HDU-1008

import java.util.Scanner;

public class Elevator {
public static void main(String[] args) {
Scanner cin=new Scanner(System.in);
int i,j,n,time;
int a[]=new int[101];
n=cin.nextInt();
while(n!=0)
{
a[0]=0;
time=0;
//输入N个数
for(i=1;i<=n;i++)
{
a[i]=cin.nextInt();
}

//记录上下楼的时间
for(j=1;j<=n;j++)
{

//上楼
if(a[j]>a[j-1])
{
time+=(a[j]-a[j-1])*6;
}
//下楼
else if(a[j]<a[j-1])
{
time+=(a[j-1]-a[j])*4;
}
time+=5;
}
System.out.println(time);
n=cin.nextInt();
}
}
}