//package competitive.akohlikashish.com.competitiveprogramming.Important_module;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;

/**
 * Created by akohlikashish on 28/03/16.
 */
class Main {
    public static void main(String[] args) {
        FastIO io = new FastIO();
        int arr[] = new int[27];
        for (int i=0;i<26;i++){
            int x = io.readInt();
            arr[i]=x;
        }

        String s = io.read();
        char[] chars = s.toCharArray();
        int maxHeight = Integer.MIN_VALUE;
        for (int i=0;i<chars.length;i++){
            maxHeight = Math.max(maxHeight,arr[chars[i]-'a']);
        }
        int area = chars.length*maxHeight;
        System.out.println(area);
    }

    static class FastIO {
        static BufferedInputStream in = new BufferedInputStream(System.in);

        static int readInt() {
            int no = 0;
            boolean minus = false;
            try {
                int a = in.read();
                while (a == 32 || a == 10) //10 is newline & 32 is ASCII for space
                    a = in.read();
                if (a == '-') {
                    minus = true;
                    a = in.read();
                }
                while (a != 10 && a != 32 && a != -1) {
                    no = no * 10 + (a - '0');
                    a = in.read();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            return minus ? -no : no;
        }

        static String read() {
            StringBuilder str = new StringBuilder();
            try {
                int a = in.read();
                while (a == 32)
                    a = in.read();
                while (a != 10 && a != 32 && a != -1) {
                    str.append((char) a);
                    a = in.read();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            return str.toString();
        }
    }
}