#!/usr/bin/perl

# http://perlmonks.org/?node_id=1191725

use strict;
use warnings;

my %hash1;
$hash1{'1'} = 1;
$hash1{'2'} = 1;
$hash1{'3'} = 1;
$hash1{'4'} = 1;
$hash1{'5'} = 1;

my %hash2;
$hash2{'1'}{key} = 'a';
$hash2{'2'}{key} = 'b';
$hash2{'3'}{key} = 'a';
$hash2{'4'}{key} = 'a';
$hash2{'5'}{key} = 'b';

print
  map $_->[2],
  sort { $a->[1] cmp $b->[1] or $a->[0] <=> $b->[0] }
  map [ $_, $hash2{$_}{'key'}, "key $_ and $hash2{$_}{'key'}\n" ],
  keys %hash1;