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];
        int height=1, high=1, width=1, area=1, temp=1;
        for(int h_i=0; h_i < 26; h_i++){
            h[h_i] = in.nextInt(); 
            //if(h_i!=0)
             //   high = (h[h_i]>h[h_i - 1])? h_i:(h_i - 1);
            //else
             //   high = h_i;
        }
        //System.out.println("high"+high);
        String word = in.next();
        //System.out.println("word"+word);
        width = word.length();
        //System.out.println("width"+width);
        for(int i=0;i<width;i++){
            temp = (int) (word.charAt(i)) - 96;
          //  System.out.println(temp);
            if(i==0)
                height = h[i];
            else
                height = (h[i]>h[i-1])? h[i]:h[i-1];
        }
        //System.out.println("height"+height);
        area = width*height;
        System.out.println(area);
    }
}