#include< stdio.h >int upward (int,int);int down (int,int);intmain(){int N , request , totaltime;int current;while(1){
scanf ("%d",&N );if( N ==0){return0;}
current =0;
totaltime =0;while( N-->0){
scanf ("%d",&request );if( request >= current ){
totaltime += upward ( current , request );}else{
totaltime += down ( current , request );}
current = request;}
printf ("%d\n", totaltime );}return0;}int upward (int current ,int target){int time;
time =6*( target - current )+5;return time;}int down (int current ,int target){int time;
time =4*( current - target )+5;return time;}