#include <iostream>
#include <string>

using namespace std;

int main()
{
    int values[26];
    for (int i = 0; i < 26; i++)
        cin >> values[i];

    string word;
    cin >> word;

    int MaxValue = -1;
    for (int i = 0; i < word.size(); i++)
    {
        char letter = word[i];
        int Value = letter - 'a';

        if (values[Value] > MaxValue)
            MaxValue = values[Value];
    }

    cout << MaxValue * MaxValue << endl;

    return 0;
}