HDU 1008 Elevator

#include<iostream>
#include<stdio.h>
#include<algorithm>
using namespace std;
int main()
{
    int n;
    while(cin>> n && n){
        int sum = 0;
        int pre = 0, x;
        for(int i=0; i<n; i++){
                cin>>x;
                if(x -pre>0){ //up
                     sum += (x-pre)*6;
                }else{ //down
                    sum += (pre-x)*4;
                }
                sum+=5;
                pre =x;
            }
            cout<<sum<<endl;
        }

    return 0;
    }