#include<iostream>
using namespace std;
int main(){
    int height[26];
    for(int i=0;i<26;i++){
        cin>>height[i];
    }
    string word;
    cin>>word;
    int max_height = 0,curr_height;;
    for(int i=0;i<word.size();i++){
        curr_height = height[word[i]-'a'];
        if(max_height< curr_height){
            max_height = curr_height;
        }
    }
    cout<<word.size()*max_height;
}