#!/bin/python

import sys


h = map(int,raw_input().strip().split(' '))
word = list(raw_input().strip())
area = 0
maxi = h[ord(word[0])-ord('a')]
for i in range(1,len(word)):
    if maxi < h[ord(word[i])-ord('a')]:
        maxi=h[ord(word[i])-ord('a')]
print maxi*len(word)