import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Ultimo {
	public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int v[] = new int[2000];
        for(int i = (int)'a'; i <= (int)'z'; i ++)
        	v[i] = Integer.parseInt(in.next());
        String s = in.next();
        int m = 0;
        for(int i = 0; i < s.length(); i ++)
        	if(v[(int)s.charAt(i)] > m)
        		m = v[(int)s.charAt(i)];
        System.out.println(m * s.length());	
	}
}