/*
 * =====================================================================================
 *
 *       Filename:  a.cpp
 *
 *    Description:  
 *
 *        Version:  1.0
 *        Created:  Tuesday 23 August 2016 09:56:30  IST
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  Shounak Dey (), dylandey1996@gmail.com
 *   Organization:  
 *
 * =====================================================================================
 */

#include<bits/stdc++.h>

using namespace std;

typedef long long int ll;

int main()
{
	ll h[26];
	for(ll i=0;i<26;i++)
		cin >> h[i];
	ll H=0;
	string s;
	cin >> s;
	for(ll i=0;i < s.length();i++)
		H = max(H,h[s[i]-'a']);
	//cout << H << endl;
	cout << H * s.length() << endl;
	return 0;
}