#include<iostream>
using namespace std;

int main(){
    int length[26];
    string s;
    for(int i = 0; i < 26; ++i)
        cin>>length[i];
    cin>>s;
    int area = s.size();
    int mx = 0;
    for(int i = 0; i < s.size(); ++i){
        if(length[s[i]-'a'] > mx)
            mx = length[s[i]-'a'];
    }
    area *= mx;
    cout<<area;



}