import java.util.*;

public class ProblemA {
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		
		int[] arr = new int[26];
		
		for(int i = 0 ; i < 26 ; i++){
			arr[i] = sc.nextInt();
		}
		
		sc.nextLine();
		
		String str = sc.nextLine();
		
		sc.close();
		
		int maxHeight = 0;
		
		for(char c : str.toCharArray()){
			maxHeight = Math.max(maxHeight, arr[c - 'a']);
		}
		
		System.out.println(maxHeight * str.length());
	}
}