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();
        char[] chars=word.toUpperCase().toCharArray();
        int length=chars.length;
        int width=1;
        int ht=0;
        for(int i=0;i<length;i++)
            {
            int pos=chars[i]-'A';
            if(h[pos]>ht)
                ht=h[pos];
        }
        System.out.println(width*length*ht);
    }
}