import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution 
{

    public static void main(String[] args) 
    {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner scan = new Scanner(System.in);
        int[] hts = new int[26];
        int loopI;
        
        for(loopI =0 ; loopI < 26; ++loopI)
        {
            hts[loopI] = scan.nextInt();
            //System.out.println(hts[loopI]);
        }
            
        String word = scan.next();
        scan.close();
        
        int width = word.length(),maxi = 0;
        
        for(loopI = 0; loopI < width; ++loopI)
        {
            char c = word.charAt(loopI);
            //System.out.println(c-92);
            if(hts[c-97]>maxi)
            {
                maxi = hts[c-97];
                //System.out.println(maxi);
            }
        }
        
        System.out.println(maxi*width);
   }
}