HDU 1008 Elevator

#include<stdio.h>
int main( )
{
    int n,sum,a,b;
    while( scanf( "%d",&n ),n )
    {
           sum = 0;
           a = 0;
           for( int i = 0; i < n; ++i )
           {
                scanf( "%d",&b );
                sum += 5;
                if( b > a )
                    sum += ( b - a ) * 6;
                if( b < a )
                    sum += ( a - b ) * 4;
                a = b;
            }
            printf( "%d\n",sum );
           }
    return 0;
}