#!/bin/python3

import sys
import string
ab = list(string.ascii_lowercase)


h = [int(h_temp) for h_temp in input().strip().split(' ')]
word = input().strip()
mapping = list(zip(ab, h))
max_height = 0
for letter in word:
    height = 0
    for abh in mapping:
        if abh[0] == letter:
            height = abh[1]
    max_height = max(height, max_height)
print(str(len(word) * max_height))