Run Length Encoding
--- ------ --------

Your task is to write a program named rle that performs
a simple form of run-length encoding, as described by
the rules below.

- The input consists of letters ('a' through 'z', both
	uppercase and lowercase), digits, spaces,
	punctuation, and newline characters.  The input
	is guaranteed to not contain any other
	characters.

- Each line in the input is encoded separately.  The
	newline at the end of each line is not encoded,
	but is passed directly to the output.  There-
	fore, the input and the output have exactly the
	same number of lines, and each line in the
	output represents the encoding of one line of
	the input.

- Any sequence of between 2 to 9 identical characters
        is encoded by two characters.  The first
	character is the length of the sequence,
	represented by the ASCII codes '2' through '9'.
	The second character is the value of the
	repeated character.
  
- Any sequence of characters that does not contain
	consecutive repetitions of any characters is
	represented by a '1' character followed by the
	sequence of characters, terminated with another
	'1'.
  
	If a '1' appears as part of the sequence, it is
	escaped with a '1'.  Therefore, whenever a '1'
	appears in a sequence, two '1's must be output.

For example, the input line "AAAAAABCCCC" would be
represented by the following seven characters:

	'6'	- The number of A's.
	'A'	- The character 'A'.
	'1'	- A marker indicating the start of a
			sequence of characters that do
			not contain consecutively
			repeated characters.
	'B'	- The character 'B'.
	'1'	- The end marker.
	'4'	- The number of C's.
	'C'	- The character 'C'.

The input line "12344" would be represented by the
following eight characters:

	'1'	- A '1' to indicate the start of a
			sequence of unrepeated
			characters
			
	'1'	- A '1' that "escapes" the following
			'1', so that it is not
			interpreted as the end of the
			sequence.
	'1'	- The escaped '1'
	'2'	- The character '2'.
	'3'	- The character '3'.
	'1'	- The '1' that marks the end of the
		  sequence.
	'2'	- The number of 4's.
	'4'	- The character '4'.

Thus:	Example Input:

	    AAAAAABCCCC
	    12344

	Corresponding Output:

	    6A1B14C
	    11123124




File:	   rle.txt
Author:	   Dan Ellard <ellard@eecs.harvard.edu>
Date:	   Sat Sep  7 10:24:09 EDT 2002

The authors have placed this file in the public domain;
they make no warranty and accept no liability for this
file.

RCS Info (may not be true date or author):

    $Author: hc3 $
    $Date: 2002/09/08 02:18:53 $
    $RCSfile: rle.txt,v $
    $Revision: 1.2 $