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;
        Hashtable<Character, Integer> alphaHeight = new Hashtable<Character, Integer>();
        char[] alphabets = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',};
        int h[] = new int[n];
        for(int h_i=0; h_i < n; h_i++){
            h[h_i] = in.nextInt();
            alphaHeight.put(alphabets[h_i], h[h_i]);
        }
        String word = in.next();
        
        int maxHeight = 0;
        for (int i=0; i<word.length(); i++) {
            char ch = word.charAt(i);
            if (alphaHeight.containsKey(ch)) {
                int he = alphaHeight.get(ch);
                if (he>maxHeight) {
                    maxHeight = he;
                }
            }
        }
        
        System.out.println(maxHeight*word.length());
    }
}