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 width = word.length();
        
        int height = Integer.MIN_VALUE;
        for(int i = 0; i < width; ++i) {
            height = Math.max(height, h[word.charAt(i)-'a']);
        }
        
        System.out.println(width*height);
    }
}