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 n =26;
        int h[] = new int[n];
        for(int h_i=0; h_i < n; h_i++){
            h[h_i] = in.nextInt();
        }
        String word = in.next();
        char arr[] = word.toCharArray();
        int max =0;
        int size = arr.length;
        for(int i=0;i<size;i++){
            int temp = (int)arr[i];
            temp = temp-97;
            int tt = h[temp];
            if(tt>max){
                max = tt;
            }
        }
        int ans = max*size;
        System.out.println(ans);
    }
}