#include <iostream>
#include <vector>
#include <algorithm>
#include <string>

using namespace std;

int main(){

	vector<int> letter;
	for(int i=0;i<26;i++)
	{
		int tmp;
		cin >> tmp;
		letter.push_back(tmp);
	}

	string word;
	cin >> word;

	int heighest = 0;
	for(int i=0;i<word.length();i++){
		if( letter[word[i] - 97] > heighest)
			heighest = letter[word[i] - 97];
	}

	cout << heighest * word.length() << endl;

}