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];
        HashMap< Character, Integer > map = new HashMap<>();
        for(int h_i=0; h_i < n; h_i++){
            h[h_i] = in.nextInt();
            map.put( ( char ) ( h_i + 97 ), h[ h_i ] );
        }
        String word = in.next();
        int ans = word.length();
        int max = 0;
        for( int i = 0; i < word.length(); i++ )
        {
            if( map.get( word.charAt( i ) ) > max )
                max = map.get( word.charAt( i ) );
        }
        System.out.println( ans * max );
    }
}