#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    vector<int> v(26);
    for (int i = 0; i < 26; ++i) {
        int a;
        cin >> a;
        v[i] = a;
    }
    string s;
    cin >> s;
    int ma = 0;
    for (int i = 0; i < s.size(); ++i) {
        int k = s[i] - 'a';
        ma = max(ma, v[k]);
    }
    ma *= s.size();
    cout << ma << endl;
    return 0;
}