#include <iostream>

using namespace std;
int f[30];
int main()
{
    for(int i = 1; i <= 26; i++)
        cin >> f[i];
    string s = "";
    getline(cin, s);
    getline(cin, s);
    int mx = 0;
    for(unsigned int i = 0; i < s.size(); i++)
        mx = max(mx, f[s[i] - 'a' + 1]);
    cout << mx * s.size();
    return 0;
}