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();
        }
        String word = in.next();
        int len=word.length();
        int max=Integer.MIN_VALUE;
        for(int i=0;i<word.length();i++){
            int curr=(int)word.charAt(i);
            if(h[curr-97]>max){
                max=h[curr-97];
            }
        }
        System.out.println(len*max);
    }
}