#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my %years =( 2007 => 
               { '01' => 07,
                 '02' => 34,
                 '10' => 24,
                 '09' => 14,
               },
            2008 =>
               { '01' => 11,
                 '02' => 64,
                 '03' => 20,
                 '09' => 13,
               },           
);

my @year_data;

foreach my $year (keys (%years))
{
    foreach my $month (keys %{$years{$year}})
    {
        push (@year_data, [$year, $month, $years{$year}{$month}]);
    }
}

@year_data = sort { my ($yearA, $monthA, $dataA) = @$a; 
                    my ($yearB, $monthB, $dataB) = @$b;
                               $dataA <=> $dataB
                                      or
                              $monthA <=> $monthB
                                      or
                               $yearA <=> $yearB
                  }@year_data;
                  
print "minimum is: @{$year_data[0]}\n";
print "maximum is: @{$year_data[-1]}\n";

#minimum is: 2007 01 7
#maximum is: 2008 02 64