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 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();
        int max=1;
        for (int i=0; i<word.length(); i++) {
            char c = word.charAt(i);
            int ind = (int) c - (int) 'a';
            if (h[ind] > max) max = h[ind];
        }
        System.out.println(max*word.length());
    }
}