#include<stdio.h>
int a[105];
int main()
{
    //freopen("1234.txt","r",stdin);
//freopen("out.txt","w",stdout);
    int n;
    while(scanf("%d",&n)!=EOF)
    {
        if(n==0)
        break;
        int sum=0;
        for(int i=1;i<=n;i++)
        scanf("%d",&a[i]);
        for(int i=1;i<=n;i++)
        {
            if(a[i]-a[i-1]>0)
            sum+=(a[i]-a[i-1])*6;
            else
            sum+=(a[i-1]-a[i])*4;
        }
        sum+=5*n;
        printf("%d\n",sum);
    }
    return 0;
}

/**************************************************************
	Problem: 2106
	User: admin
	Language: C++
	Result: Accepted
	Time:17 ms
	Memory:1144 kb
****************************************************************/