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 h[] = new int[26];
        for(int i=0; i < 26;i++){
            h[i] = in.nextInt();
        }
        String word = in.next();
        int m=0,l=word.length();
        for(int i=0;i<l;i++)
            {
            int t=word.charAt(i)-97;
            if(m<h[t])
                m=h[t];
        }
        System.out.println(m*l);
    }
}