sub minmax { ( min(@_), max(@_) ) }  # helper function

for (@list_of_Num_Extraction) {
    if (/^(\d+),(\d+):(\d+),(\d+)$/) {
        my ($l,$r, $t,$b) = (minmax($1,$3), minmax($2,$4));
        for my $x ($l .. $r) {      # left to right
            for my $y ($t .. $b) {  # top to bottom
              $Unique_Num_List{($x-1)*$num_columns + $y} = "($x,$y)";
            }
        }
    }
    # and so on ...
}

##</code><code>##

#!/usr/bin/perl -w

use strict;
use List::Util qw( min max );

sub minmax { ( min(@_), max(@_) ) }

# draw rectangles onto sparse screen matrix

my %screen;  # sparse screen matrix
my $rectangle_name = "A";
for (<DATA>) {
    if (/^(\d+),(\d+):(\d+),(\d+)$/) {
        my ($l,$r, $t,$b) = (minmax($1,$3), minmax($2,$4));
        for my $x ($l .. $r) {     # left to right
            for my $y ($t .. $b) { # top to bottom
                $screen{$y}{$x} = $rectangle_name;
            }
        }
    }
    $rectangle_name++;
}

# print out screen

for my $f (sub {$_/10 % 10}, sub {$_ % 10}, sub {"_"}) {
    print "   ", (map &$f, 1..20), "\n";
}

my ($ymin, $ymax) = minmax(keys %screen);

for my $y ($ymin .. $ymax) {
    printf "%2d|", $y;
    for my $x (1 .. 60) {
        print $screen{$y}{$x} || " ";
    }
    print "\n";
}

__DATA__
2,2:4,4
5,10:10,5
12,5:6,1
8,12:1,15

##</code><code>##

   00000000011111111112
   12345678901234567890
   ____________________
 1|     CCCCCCC                                                
 2| AAA CCCCCCC                                                
 3| AAA CCCCCCC                                                
 4| AAA CCCCCCC                                                
 5|    BCCCCCCC                                                
 6|    BBBBBB                                                  
 7|    BBBBBB                                                  
 8|    BBBBBB                                                  
 9|    BBBBBB                                                  
10|    BBBBBB                                                  
11|                                                            
12|DDDDDDDD                                                    
13|DDDDDDDD                                                    
14|DDDDDDDD                                                    
15|DDDDDDDD