import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;

class _101hack_40_1 {
	public static void main(String[] args) throws Exception {
		PrintWriter pr = new PrintWriter(System.out, true);
		InputReader in = new InputReader(System.in);
		int t,n,i,arr[],j,k,r,c,l;
		arr=new int[123];
		for(i=97;i<123;i++) arr[i]=in.readInt();
		char ch[];
		ch=in.readString().toCharArray();l=ch.length;
		long len,w;
		w=l;len=0;
		for(i=0;i<l;i++){
			if(len<arr[ch[i]]) len=arr[ch[i]];
		}
		pr.println(len*w);
		
		
	}
}
class InputReader {
    private InputStream stream;
    private byte[] buf = new byte[102400];
    private int curChar;
    private int numChars;
   
    public InputReader(InputStream stream) {
            this.stream = stream;
    }
    public final int read() {
            if (numChars == -1)
                    throw new InputMismatchException();
            if (curChar >= numChars) {
                    curChar = 0;
                    try {
                            numChars = stream.read(buf);
                    } catch (IOException e) {
                            throw new InputMismatchException();
                    }
                    if (numChars <= 0)
                            return -1;
            }
            return buf[curChar++];
    }
    public final int readInt() {
            int c = read();
            while (isSpaceChar(c))
                    c = read();
            int sgn = 1;
            if (c == '-') {
                    sgn = -1;
                    c = read();
            }
            int res = 0;
            do {
                    if (c < '0' || c > '9')
                            throw new InputMismatchException();
                    res *= 10;
                    res += c - '0';
                    c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
    }
    public final long readLong() {
            int c = read();
            while (isSpaceChar(c))
                    c = read();
            int sgn = 1;
            if (c == '-') {
                    sgn = -1;
                    c = read();
            }
            long res = 0;
            do {
                    if (c < '0' || c > '9')
                            throw new InputMismatchException();
                    res *= 10;
                    res += c - '0';
                    c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
    }
    public final String readString() {
            int c = read();
            while (isSpaceChar(c))
                    c = read();
            StringBuilder res = new StringBuilder();
            do {
                    res.appendCodePoint(c);
                    c = read();
            } while (!isSpaceChar(c));
            return res.toString();
    }
    public final  static boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }
    public final String next() {
            return readString();
    }
}