Sniffer
-------

Sniffer has the task of marking the trail through the
Hungry Woods so her pack can travel it quickly at night.
Fortunately the path does not have any forks, so no
searching is required, but sometimes its hard to see
which way the path goes.

The path and forest are represented by an array of char-
acters which is a map of the forest area.  The edges of
this map array are marked with `+'s at the corners, `-'s
at top and bottom, and `|'s at the edges.  Within the
map `#' represents impassable forest and ` ' (single
space) represents the path or open passable forest.  The
path starts at the upper left corner (array row 2,
column 2) but may exit anywhere next to a map edge.
Sniffer and her pack members can only move on the path
by going left, right, up, or down; they CANNOT go dia-
gonally.  At any point on the path there is at most one
way to continue onward.  Note that the path may run
along the edge of the map.  The path ends when there is
no way to move forward, and Sniffer knows that the path
will not deadend inside the forest (i.e., surrounded by
`#'s).

Sniffer marks the path by changing the ` ' space charac-
ters that are on the path from ` ' to `:'.


Input
-----

For each of several test cases, first a line containing
the test case name, then R lines each containing C char-
acters, which encode the array.  Each of the characters
in the R lines is `+', `-', `|', `#', or ` ' and repre-
sents one element of the array.  R is the number of rows
in the array and C the number of columns, and each row
line has exactly C characters.  The R array lines are
followed by a line containing just `.' that ends the
test case.

6 <= R,C <= 50.  No line, including the test case name
line, is longer than 80 characters.

The input ends with an end of file.


Output
------

For each test case, an exact copy of the input for the
test case, but with array characters on the path changed
from ` ' to `:'.


Sample Input
------ -----

-- SAMPLE 1 --
+----------+
|  # #### #|
|# ##    ##|
|# ## ##   |
|#    # ###|
|######    |
+----------+
.
-- SAMPLE 2 --
+------------------------------+
| #  #########    #      # #  #|
| # #        ###### #### ######|
| ### ###### ###### #  # ######|
|     ######        #  #      #|
|######     #########   #####  |
+------------------------------+
.


Sample Output
------ ------

-- SAMPLE 1 --
+----------+
|::# #### #|
|#:##::::##|
|#:##:##:::|
|#::::# ###|
|######    |
+----------+
.
-- SAMPLE 2 --
+------------------------------+
|:#  #########    #::::::# #  #|
|:# #::::::::######:####:######|
|:###:######:######:#  #:######|
|:::::######::::::::#  #::::::#|
|######     #########   #####::|
+------------------------------+
.


File:	   sniffer.txt
Author:	   Bob Walton <walton@seas.harvard.edu>
Date:	   Mon Oct 10 00:47:29 EDT 2011

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: walton $
    $Date: 2011/10/10 04:47:38 $
    $RCSfile: sniffer.txt,v $
    $Revision: 1.5 $