/*
 * Satyam Swarnkar (Zyloc), Nit Silchar
*/
#include <bits/stdc++.h>
using namespace std;
#define loop(i,start,end) for (int i=start;i<=end;i++)
#define pool(i,start,end) for(int i=start;i>=end;i--)
#define zyloc() lli t;cin>>t;while(t--)
#define vi(v) vector <long long  int> v;
#define pb(n) push_back(n)
#define mp(a,b) make_pair(a,b)
#define fill(a,value) memset(a,value,sizeof(a)) 
#define MOD 1000000007
#define PI  3.14159265358979323846
#define MAX 1000002
#define vpi(v) vector <pair <long long int, long long int> > v
#define lli long long int 
#define debug() cout<<"######"<<endl 
#define INF numeric_limits<double>::infinity()
int main(){
	lli x;
	string s;
	vi(v);
	loop(i,0,25){
		cin>>x;
		v.pb(x);
	}
	cin>>s;
	lli height(0);
	loop(i,0,s.length()-1){
		x = s[i]-'a';
		height = max(height,v[x]);
	}
	cout<<s.length()*height<<endl;
    return 0;
}