#!/bin/python

import sys
import string

h = map(int,raw_input().strip().split(' '))
word = raw_input().strip()

alphabet = list(string.ascii_lowercase)
height_dict = dict(zip(alphabet, h))

max = 1
for letter in word:
    if height_dict[letter] > max:
        max = height_dict[letter]

print max * len(word)