import java.util.*;
import java.math.*;
public class Hack101_40_1 {
  public static void main(String[] args){
	  
	  Scanner sc = new Scanner(System.in);
	  
	  Map<Character,Integer> map = new HashMap<Character,Integer>();
	  for(char ch = 'a';ch<='z';ch++)
		  map.put(ch,sc.nextInt());
	  
	  String s = sc.next();
	  
	  int max=0;
	  
	  for(int i=0;i<s.length();i++)
	  {
		  if(max<map.get(s.charAt(i)))
			  max=map.get(s.charAt(i));
	  }
	  
	  System.out.println(max*s.length());
	  
  }
}