import java.io.*;
import java.util.*;
public final class hack_august_a
{
    static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	static FastScanner sc=new FastScanner(br);
    static PrintWriter out=new PrintWriter(System.out);
	
	public static void main(String args[]) throws Exception
	{
		int[] a=new int[26];long max=0;
		for(int i=0;i<26;i++)
		{
			a[i]=sc.nextInt();
		}
		char[] b=sc.next().toCharArray();
		for(int i=0;i<b.length;i++)
		{
			max=Math.max(max,a[b[i]-'a']);
		}
		long w=b.length,res=max*w;out.println(res);out.close();
	}
}
class FastScanner
{
    BufferedReader in;
    StringTokenizer st;

    public FastScanner(BufferedReader in) {
        this.in = in;
    }
	
    public String nextToken() throws Exception {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken();
    }
	
	public String next() throws Exception {
		return nextToken().toString();
	}
	
    public int nextInt() throws Exception {
        return Integer.parseInt(nextToken());
    }

    public long nextLong() throws Exception {
        return Long.parseLong(nextToken());
    }

    public double nextDouble() throws Exception {
        return Double.parseDouble(nextToken());
    }
}