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();
        int len = word.length();
        
        int ans = len;
        int max =0;
        for (int i=0;i<len;i++){
            char  c = word.charAt(i);
            int idx = c - 'a';
            if (h[idx] > max)
                max = h[idx];
        }
        
        System.out.println(max*len);
        
    }
}