#!/bin/python

import string

h = map(int,raw_input().strip().split(' '))
word = raw_input().strip()
alpha = string.ascii_lowercase
d = {}

for i in range(26):
    d[alpha[i]] = h[i]

max_h = d[word[0]]
for i in range(1,len(word)):
    if d[word[i]]>max_h:
        max_h = d[word[i]]

print len(word)*max_h