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 < h.length; h_i++){
            h[h_i] = in.nextInt();
        }
        in.nextLine();
        String word = in.nextLine();
        int hightest = -1;
        for(int i = 0; i < word.length(); i++){
            if(h[word.charAt(i) - 'a'] > hightest){
                hightest = h[word.charAt(i) - 'a'];
            }
        }
        System.out.println(word.length()*hightest);
    }
}