#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int i,height[30],m=-1,n;
    string s;
    for(i=0;i<26;i++)
        cin>>height[i];
    cin>>s;
    n=s.size();
    for(i=0;i<n;i++){
        if(m<height[s[i]-'a'])
            m=height[s[i]-'a'];
    }
    cout<<m*n<<endl;
    return 0;
}