import java.io.IOException;
import java.io.PrintWriter;
import java.util.Scanner;

public class B {

	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		int[] h = new int[26];
		for(int i = 0;i < 26;i++)
			h[i] = sc.nextInt();
		String s = sc.next();
		int ans = 0, maxh = 0;
		for(int i = 0;i < s.length();i++)
			maxh = Math.max(maxh, h[s.charAt(i) - 'a']);
		out.println(s.length() * maxh);
		out.close();
	}
}