#!/bin/python

import sys


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

m = {}
i = 0
for l in 'abcdefghijklmnopqrstuvwxyz':
    m[l] = h[i]
    i += 1
    
width = len(word)
max = 1
for letter in word:
    if m[letter] > max:
        max = m[letter]

print max * width