#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <iomanip>

using namespace std;

#define N 26

int h[N];
string word;

int main()	{

	//freopen ("file.in", "r", stdin);
	//freopen ("file.out", "w", stdout);

	for (int i = 0; i < N; i++)
		cin >> h[i];
	cin >> word;

	int hmax = 0;
	for (int i = 0; i < word.length(); i++)
		hmax = max(hmax, h[word[i] - 'a']);
		
	cout << hmax*word.length() << endl;	

	return 0;
}