#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 a[26] = { 0 };
    for(int i = 0; i < 26; i++){
        cin>>a[i];
    }
    string str;
    cin>>str;
    int i = 0;
    long int max = INT_MIN;
    while(str[i] != '\0'){
        long int temp = a[str[i]-'a'];
        if(temp > max){
            max = temp;
        }
        i++;
    }
    //long int area = i;
    cout<<i*max<<endl;
    return 0;
}