using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution {

    static void Main(String[] args) {
        string[] h_temp = Console.ReadLine().Split(' ');
        int[] h = Array.ConvertAll(h_temp,Int32.Parse);
        string word = Console.ReadLine();
        int max = -1;
        for(int i=0;i<word.Length;i++)
            if(max<h[word[i]-'a'])
            {
                max=h[word[i]-'a'];
            }
        Console.WriteLine(max*word.Length);
    }
}