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 sc = new Scanner(System.in);


      int[] height = new int[26];

      for (int i = 0; i < 26; i++) {
         height[i] = sc.nextInt();
      }

      sc.nextLine();
      String s = sc.nextLine();
      
      int maxHeight = 1;
      for (int i = 0; i < s.length(); i++) {
         int index = s.charAt(i) - 'a';

	 if (height[index] > maxHeight) {
	    maxHeight = height[index];
	 }
      }

      System.out.println(maxHeight * s.length());
   }

}