#include<bits/stdc++.h>
using namespace std;

int main(int argc, char **argv) {
	int h[26], m = -1;
	for (int i = 0; i < 26; i++)
		cin >> h[i];
	string w;
	cin >> w;
	for (int i = 0; i < w.length(); i++)
		m = max(h[ w[i] - 'a'], m);
	cout << m * w.length();
	return 0;
}