import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
    
    
    private static long calArea(int[] h, String word){
        word= word.trim();
        int max_height = Integer.MIN_VALUE;
        for(int i=0;i<word.length();i++){
            max_height= Math.max(max_height, h[(word.charAt(i) - 97)]);            
        }        
        return max_height*1*word.length();        
    }

    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();
        System.out.println(calArea(h,word));
    }
}