import java.awt.Point;
import java.io.*;
import java.io.ObjectInputStream.GetField;
import java.math.BigInteger;
import java.sql.Array;
import java.util.*;
import java.util.jar.Attributes.Name;
import java.util.logging.Level;

class TestClass {
 
	static long mod ;
	static int[][] C;
	static boolean[][] G;
	static int Root;
	static int[] S;
	static int[] A;
	static int min=Integer.MAX_VALUE;
	static int temp;
	static ArrayList<Batman>[] M;
	 
    static class Batman{
	     int x;
	     int value;
	     int next;
	     public Batman(int x , int value, int next){
			 this.x=x;
			 this.value = value;
			 this.next = next;
		}
}

 
public static double Area(double R , double r , double d){
	
	
	Double part1 = r*r*Math.acos((d*d + r*r - R*R)/(2*d*r));
	Double part2 = R*R*Math.acos((d*d + R*R - r*r)/(2*d*R));
	Double part3 = 0.5*Math.sqrt((-d+r+R)*(d+r-R)*(d-r+R)*(d+r+R));

     return  (part1 + part2 - part3);
}


	
public static void main(String args[] ) throws java.lang.Exception {
 
 
 
InputStream inputStream = System.in;
InputReader in = new InputReader(inputStream);
 
//BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
//BufferedReader in = new BufferedReader(new FileReader("C:\\Users\\Sompathak\\Desktop\\yes.txt"));
//Scanner in = new Scanner(new FileReader("C:\\Users\\Sompathak\\Desktop\\yes.java"));
//PrintWriter pw = new PrintWriter(new FileWriter("C:\\Users\\sompathak\\Desktop\\output.txt"));
//InputStream inputStream = System.in;
//InputReader in = new InputReader(inputStream);
//Scanner in = new Scanner(new InputStreamReader(System.in));
//Scanner in = new Scanner(new FileReader("C:\\Users\\sompatha\\Desktop\\yes.txt"));
//we can we will ??? !!!!!! SOM RISES
//long startTime = System.currentTimeMillis();
//long startTime = System.currentTimeMillis();
 
//float endTime   = System.currentTimeMillis();
//float totalTime = (endTime - startTime)/(float)1000;
//System.out.println(totalTime+" sec....."); 

 //in.hasNext()
int[] A = new int[26];
for(int i=0;i<26;i++) A[i] = in.nextInt();
String S = in.next();
int h=0;
for(int i=0;i<S.length();i++) h = Math.max(h,A[S.charAt(i)-'a']);
System.out.println(h*S.length());



}public 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 nextInt()
{
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, nextInt());
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, nextInt());
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);
}
}
}