#!/usr/bin/perl

use strict;
use warnings;

my %HoH = (
           www => { wwe => 11, wte => 21, wee => 0},
           zzz => { zze => 15 },
          );

my @keys = sort {
    $HoH{$a->[0]}{$a->[1]} <=>
    $HoH{$b->[0]}{$b->[1]}
} map {
    my $outter = $_;
    map {
        [ $outter, $_ ]
    } keys %{$HoH{$outter}};
} keys %HoH;

for (@keys)
{
    print( (join '::', @$_), ' = ', $HoH{$_->[0]}{$_->[1]}, "\n");
}