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 n = 26;
        int h[] = new int[n];
        for(int h_i=0; h_i < n; h_i++){
            h[h_i] = in.nextInt();
        }
        String word = in.next();
            int result = -1;
            for(int i = 0; i < word.length(); i++)
                    result = Math.max(result, h[(int)word.charAt(i) - (int)'a']);
           System.out.println(word.length()*result);
    }
}