#!/bin/python

import sys


h = map(int,raw_input().strip().split(' '))
word = raw_input().strip()
word=list(word)
l=len(word)
x={}
a=97
for i in h:
    x[chr(a)]=i
    a+=1
y=[]
for j in word:
    y.append(x[j])
print(max(y)*l)