#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;


int main(){
    int n = 26, max = 0, index;
    vector<int> h(n);
    for(int h_i = 0;h_i < n;h_i++){
       cin >> h[h_i];
    }
    string word;
    cin >> word;
    int length, height, area;
    length = word.length();
    for(int i = 0; i < word.length(); i++){
        index = word[i] - 'a';
        if(h[index] > max)
            max = h[index];
    }
    height = max;
    area = (length * height);
    cout << area;
    return 0;
}