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[26];
		for (int h_i = 0; h_i < 26; h_i++) {
			h[h_i] = in.nextInt();
		}
		String word = in.next();
		solver(word, h);
	}
	
	public static void solver(String word, int[] h){
		char []c =  word.toCharArray();
		int maxHeight = -1;
		for(int i = 0 ; i < c.length; i++){
			if(h[c[i]-'a'] > maxHeight)
				maxHeight = h[c[i]-'a']; 
		}
		
		int maxArea = word.length() * maxHeight;
		System.out.println(maxArea);
	}
}