//	Author: Mohib Manva
#include <bits/stdc++.h>
using namespace std;

#define ll long long 
#define vi vector<int>
#define vll vector<long long>
#define pb push_back
#define mk(a,b) make_pair(a,b)
#define pi pair<int,int>
#define ff first
#define ss second
#define vpi vector<pair<int,int> >
#define all(s) s.begin(),s.end()
#define fast ios_base::sync_with_stdio(false)
#define TC() fast;int t;scanf("%d",&t);while(t--)

const int mod=(int)1e9+7;
const int MAXN=10000000;


int main(){
	long long int ar[26];
    for(int i=0;i<26;i++)
        cin>>ar[i];
    char str[1001];
    long long ma = 0;
    scanf("%s",str);
    long long ans = strlen(str);
    for(int i=0;str[i]!=0;i++){
        ma = max(ma,ar[str[i]-'a']);
    }
    printf("%lld\n",ans*ma);
	return 0;
}