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 n = 26;
        int h[] = new int[n];
        for(int h_i=0; h_i < n; h_i++){
            h[h_i] = in.nextInt();
        }
        String word = in.next();
        
        int max = findMaxHeight(word, h, word.length());
        
        System.out.println(max);
    }

	private static int findMaxHeight(String word, int[] h, int len) {
		// TODO Auto-generated method stub
		int max = Integer.MIN_VALUE;
		for(int i=0;i<len;i++){
			int pos =word.charAt(i)-'a';
			if(h[pos]>max){
				max = h[pos];
			}
		}
		return max*len;
	}
}