import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;
import java.util.StringTokenizer;

/**
 * Created by pallavi on 23/8/16.
 */
public class PDF {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer tokenizer = new StringTokenizer(reader.readLine());
        Map<Character, Integer> h = new HashMap<>();
        char ch = 'a';
        for (int i = 0; i < 26; i++) {
            h.put(ch, Integer.parseInt(tokenizer.nextToken()));
            ch += 1;
        }
        char[] s = reader.readLine().toCharArray();
        int mh = 0;
        for (int i = 0; i < s.length; i++) {
            mh = Math.max(mh, h.get(s[i]));
        }
        System.out.println(mh*s.length);
    }
}