import java.io.*;
import java.util.Arrays;
import java.util.InputMismatchException;
 

class First {

    public static void main(String[] args) throws Exception
    {
        long[] f = new long[26];
        for( int i=0 ; i<26 ; i++ ) f[i]=i();
        char[] c = s().toCharArray();
        long max = -1;
        for( int i=0 ; i<c.length ; i++ ){
        	max = Math.max(f[c[i]-'a'], max);
        }
        out.println(c.length*max);
        out.close();
        
    }
 
 	
 	
    static InputReader in = new InputReader(System.in);
    static OutputWriter out = new OutputWriter(System.out);
    
    static int i()
    {
    	return in.readInt();
    }
    
    static long l()
    {
    	return in.readLong();
    }
    
    static double d()
    {
    	return in.readDouble();
    }
    
    static String s()
    {
    	return in.readString();
    }
    
    static void Iarr( int[] array, int no )
    {
    	for( int i=0 ; i<no ; i++ )
    	{
    		array[i] = i(); 
    	}
    }
    
    static void Larr( long[] array, int no )
    {
    	for( int i=0 ; i<no ; i++ )
    	{
    		array[i] = l(); 
    	}
    }
    
    static void Darr( double[] array, int no )
    {
    	for( int i=0 ; i<no ; i++ )
    	{
    		array[i] = d(); 
    	}
    }
    
    static void Sarr( String[] array, int no )
    {
    	for( int i=0 ; i<no ; i++ )
    	{
    		array[i] = s(); 
    	}
    }
    
    private static class InputReader
    {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;
 
        public InputReader(InputStream stream)
        {
            this.stream = stream;
        }
 
        
        
        
        
        
        
        public 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 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 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 double readDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, readInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, readInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }
        public 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 boolean isSpaceChar(int c)
        {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }
 
        public String next()
        {
            return readString();
        }
 
        public interface SpaceCharFilter
        {
            public boolean isSpaceChar(int ch);
        }
    }
 
    private static class OutputWriter
    {
        private final PrintWriter writer;
 
        public OutputWriter(OutputStream outputStream)
        {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }
 
        public OutputWriter(Writer writer)
        {
            this.writer = new PrintWriter(writer);
        }
 
        public void print(Object... objects)
        {
            for (int i = 0; i < objects.length; i++)
            {
                if (i != 0)
                    writer.print(' ');
                writer.print(objects[i]);
            }
        }
 
        public void println(Object... objects)
        {
            print(objects);
            writer.println();
        }
 
        public void close()
        {
            writer.close();
        }
 
        public void flush()
        {
            writer.flush();
        }
     }
}