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

int main()
{
    auto heights = array<int, 26>{};
    for (auto& x : heights) cin >> x;

    string s; cin >> s;

    auto max_height = 0;
    for (auto c : s)
        max_height = max(max_height, heights[c-'a']);

    cout << max_height * s.length() << endl;
}