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

public class Solution {

    private static int maxim;
    private static int[] height = new int[26];
    private static String word;
    
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        for ( int i = 0 ; i < 26 ; i ++ ) {
            height[i] = scanner.nextInt();
        }
        
        word = scanner.next();
        for ( int i = 0 ; i < word.length() ; i ++ ) {
            int index = Character.getNumericValue(word.charAt(i)) - Character.getNumericValue('a');
            if ( height[index] > maxim ) {
                maxim = height[index];
            }
        }
        
        int solution = maxim * word.length();
        System.out.println(solution);
    }
}