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[27];
        for(int h_i=0; h_i < 26; h_i++){
            h[h_i] = in.nextInt();
        }
        String word = in.next();
        int maxHeight  = 0;
        for (char letter : word.toCharArray()){
            if (h[letter - 97] > maxHeight){
                maxHeight = h[letter - 97];
            }
        }
        
        System.out.println(maxHeight * word.length());
    }
}