10
a l
11
b m

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;

my $filename = $ARGV[0];
my $outFilename = $ARGV[1];
open OUTFILE, ">", $outFilename or die $!;


open FILE, $filename or die $!;

my $id;
my $date;

while(<FILE>)
{
	my $line = $_;
	if($_ =~ /(.*?)\t+(.*?)\[/ ) {
		$id = $1;
		$date = $2;
		print OUTFILE "$id\t$date\n";
	}

my $key;
my $i;
my %HoA;

push @{ $HoA{$id} }, $date;
	

my $k;
foreach $k (keys %HoA) {
	print "$k\n\t";
   foreach (@{$HoA{$k}}) {
      print " $_";
   }
   print "\n";
}
}

##</code><code>##

10		a[
11		b[
12		c[
13		d[
14		e[
15		f[
16		g[
17		h[
18		i[
19		j[
20		k[
10		l[
11		m[
12		n[
13		o[
14		p[
15		q[
16		r[
17		s[
18		t[
19		y[
20		v[

##</code><code>##

10
	 a
11
	 b
12
	 c
13
	 d
14
	 e
15
	 f
16
	 g
17
	 h
18
	 i
19
	 j
20
	 k
10
	 l
11
	 m
12
	 n
13
	 o
14
	 p
15
	 q
16
	 r
17
	 s
18
	 t
19
	 y
20
	 v