#!/usr/bin/perl

use strict;
my %HoH;
my $months;
my $key;
my %seen;
my @uniq;
my $client;
my $Months_count;

while (<DATA>) {
        ($client,$Months_count) = split /\|/, $_;

        my %by_month = split ' ', $Months_count;
        $HoH{$client} = \%by_month;

}

while ( ($client, $months) = each %HoH ) {

    while (defined ($key = each %$months)) {
        $seen{$key}++;
    }
    @uniq = keys %seen;
}
print "@uniq\n";
__DATA__
IBM | February 1 March 5 July 4
Oracle| January 3 March 4 April 6 May 5
RedHat | March 2 June 3 August 1