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

public class Hack101_40_1 {

	public static void main(String[] args) {
		InputReader s = new InputReader(System.in);
		PrintWriter out = new PrintWriter(System.out);
		/*My code starts here.*/
		int arr[] = new int[26];
		for(int i=0;i<26;i++)
			arr[i] = s.nextInt();
		String tmp = s.readString();
		int len = tmp.length();
		int max = Integer.MIN_VALUE;
		for(int i=0;i<len;i++){
			if(max<(arr[tmp.charAt(i)-'a']))
				max = arr[tmp.charAt(i)-'a'];
		}
		out.println(max * len);
		/*My code ends here.*/
		out.close();
	}

	static class Node implements Comparable<Node> {
		int num, freq, idx;

		public Node(int u, int v, int idx) {
			this.num = u;
			this.freq = v;
			this.idx = idx;
		}

		public int compareTo(Node n) {
			if (this.freq == n.freq)
				return Integer.compare(this.num, n.num);
			return Integer.compare(-this.freq, -n.freq);
		}
	}

	static class InputReader {

		private InputStream stream;
		private 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);
		}
	}
}