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 maxHeight  = -1;
        int length = word.length();
        for(char c: word.toCharArray()) {
            if(h[(int)c-(int)'a'] > maxHeight)
                maxHeight = h[(int)c-(int)'a'];
        }
        System.out.println(length*maxHeight);
    }
}