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();
        
        int height = 0;
        for(char c: word.toCharArray()) {
            int i = c - 'a';
            int v = h[i];
            
            if(v > height) {
                height = v;
            }
        }
        
        int area = word.length() * height;
        System.out.println(area);
    }
}