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();
        Console.WriteLine(word.Length * word.Select(c => h[c - 'a']).Max());
    }
}