import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.StringTokenizer;

public class Solution {

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub

			BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
			BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));
			
			StringTokenizer st = new StringTokenizer(in.readLine());
			
			int arr[] = new int[26];
			
			for(int i = 0; i < 26; i++) {
				arr[i] = Integer.parseInt(st.nextToken());
			}
			
			String s = in.readLine();
			
			int len = s.length();
			
			long max = 0;
			for(int i = 0; i < len; i++) {
				char x = s.charAt(i);
				
				max = Math.max(arr[x - 'a'], max);
			}
			
			max = max * len;
			
			out.write(max+"\n");
			
			
			out.close();
			

	}

}