import java.io.*;
	import java.math.*;
	import java.text.*;
	import java.util.*;
	 
	public class Solution {
	 
		static double eps=(double)1e-7;
		static long mod=(int)1e9+7;
		public static void main(String args[]){
			InputReader sc = new InputReader(System.in);
			OutputStream outputStream = System.out;
			PrintWriter out = new PrintWriter(outputStream);
			//----------My Code----------
			
			
			int[] arr=new int[26];
			
			for(int i=0;i<26;i++)
			{
				arr[i]=sc.nextInt()*-1;
			}
			
			String s=sc.nextLine();
			
			PriorityQueue<Integer> pq=new PriorityQueue<Integer>();
			
			for(int i=0;i<s.length();i++)
			{
				pq.add(arr[s.charAt(i)-'a']);
			}
			
			out.println(s.length()*pq.peek()*-1);
			out.close();
			//---------------The End------------------
	 
		}
	 
		
		
		static long modulo(long a,long b,long c) {
			long x=1;
			long y=a;
			while(b > 0){
				if(b%2 == 1){
					x=(x*y)%c;
				}
				y = (y*y)%c; // squaring the base
				b /= 2;
			}
			return  x%c;
		}
		static long gcd(long x, long y)
		{
			if(x==0)
				return y;
			if(y==0)
				return x;
			long r=0, a, b;
			a = (x > y) ? x : y; // a is greater number
			b = (x < y) ? x : y; // b is smaller number
			r = b;
			while(a % b != 0)
			{
				r = a % b;
				a = b;
				b = r;
			}
			return r;
		}
	}
		 class InputReader {
			public BufferedReader reader;
			public StringTokenizer tokenizer;
	 
			public InputReader(InputStream inputstream) {
				reader = new BufferedReader(new InputStreamReader(inputstream));
				tokenizer = null;
			}
	 
			public String nextLine(){
				String fullLine=null;
				while (tokenizer == null || !tokenizer.hasMoreTokens()) {
					try {
						fullLine=reader.readLine();
					} catch (IOException e) {
						throw new RuntimeException(e);
					}
					return fullLine;
				}
				return fullLine;
			}
			public String next() {
				while (tokenizer == null || !tokenizer.hasMoreTokens()) {
					try {
						tokenizer = new StringTokenizer(reader.readLine());
					} catch (IOException e) {
						throw new RuntimeException(e);
					}
				}
				return tokenizer.nextToken();
			}
			public long nextLong() {
				return Long.parseLong(next());
			}
			public int nextInt() {
				return Integer.parseInt(next());
			}
		}