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) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] lengths = br.readLine().split(" ");
        String ip = br.readLine();
        int max_height = Integer.MIN_VALUE;
        for(int i=0;i<ip.length();i++){
            int height = Integer.parseInt(lengths[ip.charAt(i)-'a']);
            if(height > max_height){
                max_height = height;
            }
        }
        System.out.println(max_height*ip.length());
    }
}