PAT 1008

#include<cstdio>
#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
#include<queue>
#include<map>
#include<set>
using namespace std;



int main()
{

	//freopen("input.txt","r",stdin);
	int n;
	cin>>n;

	int a[100100];
	a[0]=0;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
	}
	int sum=0;
	for(int i=1;i<=n;i++)
	{
		if(a[i]>=a[i-1])
			sum+=(a[i]-a[i-1])*6+5;
		else
			sum+=(a[i-1]-a[i])*4+5;
	}
	PRintf("%d",sum);
	//freopen("con","r",stdin);

	system("pause");
	return 0;
}