#include<stdio.h>
int n,d,i,s,sum,k;
int main()
{
	while(~scanf("%d",&n)&&n)
	{
		d=0;sum=0;
		for(i=1;i<=n;i++)
		 {
		 	scanf("%d",&s);
		 	k=s-d;
		 	if(k>0) sum+=6*k;
		 	else sum+=-4*k;
		 	d=s;
		 }
		 sum+=n*5;
		 printf("%d\n",sum);
	}
	return 0;
}
/**************************************************************
	Problem: 2106
	User: admin
	Language: C
	Result: Accepted
	Time:20 ms
	Memory:1144 kb
****************************************************************/