import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;

public class Solution {
	public static void main(String[] args) throws IOException{
		Scanner sc = new Scanner(System.in);
		//BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		int[] heights = new int[26];
		
		for(int i = 0; i<26; i++){
			heights[i] = sc.nextInt();
		}
		
		String S = sc.next();
		
		int width = S.length();
		int height = 0;
		for(char c : S.toCharArray()){
			int ind = c - 'a';
			height = Math.max(height, heights[ind]);
		}
		
		System.out.println(width*height);
		
	}
}