my ($prevDateHour,%curHour);
while (<>) {
    my ($dateHour, $usrMac, $apMac) = parsit();
    if ($dateHour ne $prevDateHour) {
        for my $ap (sort keys %curHour) {
            print $prevDateHour, $ap, scalar(keys %{$curHour{$ap}}), "\n";
        }
        %curHour=();
        $prevDateHour = $dateHour;
    }
    $curHour{$apMac}{$usrMac} = 1;
}