#include<iostream>
using namespace std;
int main()
{
	int n;
	cin>>n;
	int n1 = 0, n2, t = 0;
	for(int i=0; i<n; i++){
		cin>>n2;
		n2>n1 ? t += (n2-n1)*6 : t += (n1-n2)*4;
		n1 = n2; 
	}
	t += n*5;
	cout<<t;
	
	return 0;
 }