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 alph[] = new int[28];
        for (int i = 0; i < 26; i++) {
            alph[i] = in.nextInt();
        }
        int res = 0;
        String read = in.next();
        int max = 0;
        for (int i = 0; i < read.length(); i++) {
            if(alph[read.charAt(i)-97]>max) max = alph[read.charAt(i)-97];
        }
        System.out.println(max*read.length());
        
        
    }
}