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

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
		
		int h[] = new int[30];
		for (int i=0;i<26;i++){
			h[i] = in.nextInt();
		}
		
		String word = in.next();
		
		
		int width = word.length();
		int height = 0;
		for (int i=0;i<word.length();i++){
			
			int p = word.charAt(i) - 'a';
			if (h[p]> height)height = h[p];
		}
		int ans = width * height;
		System.out.println(ans);
		
		
		
		in.close();
        
        
        
        
    }
}