#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

char s[20];
int num[30];

int main () {
    for (int i = 0; i < 26; i++)    cin >> num[i];
    cin >> s;
    int len = strlen (s);
    int maxn = 0;
    for (int i = 0; i < len; i++)   maxn = max (maxn, num[s[i] - 'a']);
    cout << len * maxn << endl;
    return 0;
}