import java.util.*;
import java.io.*;


/**
 *
 * @author Umang Upadhyay
 */
public class ProblemA {
    
    public static int mod = 1000000007;
    
    public static long pow(long x,long y,long m){
        long temp;
        if(y==0) return 1;
        
        temp = (pow(x,y/2,m))%m;
        if(y%2==0) return ((temp*temp)%m);
        else return (((x*temp)%m*temp)%m);
    }
    
    public static void main(String[] args) {
        
        InputReader in = new InputReader(System.in);
        PrintWriter w = new PrintWriter(System.out);
        
        int[] arr = new int[26];
        
        for(int i=0;i<26;i++) arr[i] = in.nextInt();
        String s = in.readString();
        
        long ans = 1;
        ans =s.length();
        int max = 0;
        for(int i=0;i<s.length();i++){
            if(arr[s.charAt(i)-'a']>max) max = arr[s.charAt(i)-'a'];
        }
        ans*=max;
        w.println(ans);
        w.close();
        
    }
    
    static class InputReader {

		private final InputStream stream;
		private final byte[] buf = new byte[8192];
		private int curChar, snumChars;
		private SpaceCharFilter filter;

		public InputReader(InputStream stream) {
			this.stream = stream;
		}

		public int snext() {
			if (snumChars == -1)
				throw new InputMismatchException();
			if (curChar >= snumChars) {
				curChar = 0;
				try {
					snumChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (snumChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public int nextInt() {
			int c = snext();
			while (isSpaceChar(c))
				c = snext();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = snext();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = snext();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public long nextLong() {
			int c = snext();
			while (isSpaceChar(c))
				c = snext();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = snext();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = snext();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int[] nextIntArray(int n) {
			int a[] = new int[n];
			for (int i = 0; i < n; i++)
				a[i] = nextInt();
			return a;
		}

		public String readString() {
			int c = snext();
			while (isSpaceChar(c))
				c = snext();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = snext();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public boolean isSpaceChar(int c) {
			if (filter != null)
				return filter.isSpaceChar(c);
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		public interface SpaceCharFilter {
			public boolean isSpaceChar(int ch);
		}
	}
}