#!/usr/bin/perl

use strict;
use warnings;

my %HoA;

while (<DATA>) {
	if (/(\d+)\s+(.*?)\[/) {
		push @{$HoA{$1}}, $2;

	} else {
		warn "Unknown data format: $_\n";
	}
}

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

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