#!/usr/bin/perl
use strict;
use warnings;

my @clusters;

chomp (my @lines = <DATA>);


foreach my $line (0..$#lines) {

    my @ids = $lines[$line] =~ m/\.(\S+)/g;

    my $in_cluster;

    foreach my $cluster (0..$#clusters) {
        if ( map { my $id = $_; grep { $id eq $_ } @ids } @{$clusters[$cluster]->{ids}} ) {
            if(defined($in_cluster)) {
                push(@{$clusters[$in_cluster]->{lines}}, @{$clusters[$cluster]->{lines}});
                push(@{$clusters[$in_cluster]->{ids}}, @{$clusters[$cluster]->{ids}});
                splice(@clusters,$cluster,1);
                last;
            } else {
                $in_cluster = $cluster;
                push(@{$clusters[$cluster]->{lines}}, $line);
                push(@{$clusters[$cluster]->{ids}}, @ids);
            }
        }
    }
    unless(defined($in_cluster)) {
        my $cluster = {};
        push(@{$cluster->{lines}}, $line);
        push(@{$cluster->{ids}}, @ids);
        push(@clusters, $cluster);
    }
}


foreach my $cluster (0..$#clusters) {
    print "Cluster number " . ($cluster + 1) . ":\n";
    foreach my $line (sort { $a <=> $b } @{$clusters[$cluster]->{lines}}) {
        print "\t$lines[$line]\n";
    }
    print "\n";
}

exit(0);

__DATA__
ID5141.C1665 ID5141.C2448
ID5141.C1253 ID5144.C2039
ID5141.C1596 ID5144.C1956
ID5141.C1906 ID5144.C2149
ID5141.C1221 ID5144.C1956
ID5141.C2149 ID5141.C2386
ID5141.C2039 ID5142.C1221
ID5141.C5887 ID5141.C7685
ID5141.C1005 ID5142.C2808
ID5141.C1046 ID5141.C1596
ID5141.C2386 ID5141.C4990
ID5141.C7685 ID5141.C4888