import java.util.Scanner;

public class DesignerPdfViewer {

	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int[] h = new int[26];
		for (int i = 0; i < 26; i++) {
			h[i] = in.nextInt();
		}
		String word = in.next();
		int maxHeight=-1;
		for (int i = 0; i < word.length(); i++) {
			int height = h[(int)word.charAt(i)-97];
			if(height>maxHeight){
				maxHeight=height;
			}
		}
		System.out.println((maxHeight*word.length()));
	}

}