#!/usr/bin/perl

use warnings;
use strict;

my %eventHash = ();

while (my $line = <DATA>) {
    chomp $line;
    my ($time, $event) = split /;/, $line, 2;
    push @{$eventHash{$time}}, $event;
}


print "$_\n" for @{$eventHash{56003}};

__DATA__
56000;some;thing;happened;here;1
56000;some;thing;happened;here;2
56003;some;thing;happened;here;3
56003;some;thing;happened;here;4
56004;some;thing;happened;here;5
56009;some;thing;happened;here;6
56009;some;thing;happened;here;7
56009;some;thing;happened;here;8
56010;some;thing;happened;here;9