import java.io.*;

class UseCharListsA2
{
// A program which reads and writes lists of characters
// in their conventional form.

 public static void main(String[] args) 
 throws IOException
 {
  BufferedReader in = new BufferedReader(
                        new InputStreamReader(System.in));
  CharListA L1,L2;
  System.out.print("Enter first list of characters: ");
  L1 = readCharListA(in);
  System.out.print("Enter second list of characters: ");
  L2 = readCharListA(in);
  System.out.print("The lists are: ");
  printCharListA(L1);
  System.out.print(" and  ");
  printCharListA(L2);
  System.out.println();
 }

 public static void printCharListA(CharListA L)
 {
  System.out.print("[");
  if(L!=null)
     {
      System.out.print(L.head);
      for(CharListA ptr=L.tail;ptr!=null;ptr=ptr.tail)
          System.out.print(","+ptr.head);
     }
  System.out.print("]");
 }

 public static CharListA readCharListA(BufferedReader in) 
 throws IOException
 {
  String line = in.readLine();
  int i=0;
  CharListA L=null;
  try {
       if(line.charAt(i)!='[')
          {
           System.out.print("Error - expected '[',");
           System.out.println(" found '"+line.charAt(i)+"'");
           return null;
          }
       if(line.charAt(++i)==']')
          return null;
       L = new CharListA(line.charAt(i++),null);
       for(CharListA ptr=L; line.charAt(i++)==',' ;ptr=ptr.tail)
          ptr.tail = new CharListA(line.charAt(i++),null);
       if(line.charAt(i-1)!=']')
          {
           System.out.print("Error - expected ']' or ','");
           System.out.println(", found '"+line.charAt(i-1)+"'");
          }
       if(i!=line.length())
          {
           System.out.print("Error - extra characters: \"");
           System.out.println(
            line.substring(i,line.length())+"\"");
          }
      }
  catch(StringIndexOutOfBoundsException e)
      {
       System.out.print("Error - unexpected ");
       System.out.println("end of line");
      }
  return L; 
 }
}