import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Pdf {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
       
        HashMap<Character,Integer> heightMap = new HashMap<>();
        for(int h_i=0; h_i < 26; h_i++){
            heightMap.put((char)('a'+h_i),in.nextInt());
            //h[h_i] = in.nextInt();
        }
        
        String word = in.next();
        int height = 0;
        for(char c : word.toCharArray()){
            height = Math.max(height, heightMap.get(c));
        }
        System.out.println((height*word.length()));
    }
}