#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define li long int
#define vi vector<int> 
#define vvi vector< vector <int,int> >
ll mod=1e9+7;
map<int,int> val;

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	ll p;
	for(int i=0;i<26;i++){
		cin>>p;
		val[i]=p;
	}
	string str;
	cin>>str;
	ll sum=0;
	for(int i=0;i<str.length();i++)
		sum=val[str[i]-'a']>sum?val[str[i]-'a']:sum;
	cout<<(sum*str.length())<<endl;
	
}