import java.util.Scanner;




public class Solution//for hackerrank add public and for codeChef, remove public
{
    
    private static boolean test=false;
        public static void main(String[] args) throws Exception
    {        
        Scanner sc=new Scanner(System.in);
        int i,t,n;
       
        
        int[] val=new int[26];
        for(i=0;i<26;i++)
        {
           val[i]=sc.nextInt();
        }
        String s=sc.next();
        int area=s.length();
        int max=-1;        
        for(i=0;i<area;i++)
        {
            int temp=val[s.charAt(i)-'a'];
            if(temp>max)
                max=temp;
        }
        area*=max;
        
        System.out.println(area);
        
        
            
                 
        
        }
    
}