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)
        {
            max = Math.Max(h[word[i]- 'a'], max);
        }
        
        Console.WriteLine(max * word.Length);
    }
}