#!/usr/bin/perl
#use warnings;
##</code><code>##

use strict;

##</code><code>##

open my $graph, '<', '2211.txt' or
  die "Can't open `2211.txt': $!\n";

##</code><code>##

while (<GRAPH>)
{
        $a1 = push(@a1, $1);
        $a2 = push(@a2, $2);
    print @a1, @a2;
}
##</code><code>##

while (<GRAPH>)
{
        /$some $regex ($with) ($parens)/;
        $a1 = $1;
        $a2 = $2;
        print $a1, $a2;
}

##</code><code>##

my (@a1, @a2);
while (<GRAPH>)
{
        /$some $regex ($with) ($parens)/;
        push @a1, $1;
        push @a2, $2;
}
print @a1, @a2;