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) {
        Scanner in = new Scanner(System.in);
        int h[] = new int[26];
        for(int h_i=0; h_i < 26; h_i++){
            h[h_i] = in.nextInt();
        }
        String word = in.next();
        
        int result = word.length();
        int max_h = -1;
        
        for (int i = 0; i < word.length(); i++)
            if (h[word.charAt(i)-97] > max_h)  max_h = h[word.charAt(i)-97];
            
        result *= max_h;
        
        System.out.println(result);
        
        
    }
}