import java.io.*;
import java.util.*;

class IO
{
	static BufferedReader reader;
	static StringTokenizer tokenizer;
	static PrintWriter writer;
	static void initialise(InputStream in, OutputStream out)
	{
		reader=new BufferedReader(new InputStreamReader(in));
		tokenizer=new StringTokenizer("");
		writer=new PrintWriter(new BufferedWriter(new OutputStreamWriter(out)));
	}
	static String next()
	{
		try
		{
			while(tokenizer==null||!tokenizer.hasMoreElements())
			{
				tokenizer=new StringTokenizer(reader.readLine());
			}
			return tokenizer.nextToken();
		}
		catch(IOException exc)
		{
			System.out.println("I/O error has occurred");
			return (null);
		}
	}
	static int nextInt()
	{
		return(Integer.parseInt(next()));
	}
	static void write(int i)
	{
		writer.println(i);
	}
	static void write(String i)
	{
		writer.println(i);
	}
	static void close()
	{
		writer.flush();
		writer.close();
	}
	
}



class Question1 
{
	public static void main(String args[])
	{
		IO.initialise(System.in,System.out);
		int n,i,j,m,k;
		int height[]=new int[26],length,area,maxHeight;
		String word;
			area=0;
			maxHeight=0;
			for(i=0;i<26;++i)
				height[i]=IO.nextInt();
			word=IO.next();
			length=word.length();
			area=length;
			for(i=0;i<length;++i)
            {
				maxHeight=Math.max(height[word.charAt(i)-'a'], maxHeight);
            }
			area*=maxHeight;
		IO.write(area);
		IO.close();
	}
}