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();
        in.close();
        
        int width = word.length();
        
        int height = 0;
        for (int i = 0; i < width; i++) {
            int hhh = h[(int)(word.charAt(i) - 'a')];
            if (hhh > height) {
                height = hhh;
            }
            
          
        }
        
        System.out.println(width * height);
    }
}