#!/usr/bin/perl -w
use strict;

my %hash = (
	    'I' => 1,
	    'II' => {
		'A' => 3,
		'B' => {
		    '1' => 4,
		    '2' => 5,
		    '3' => 6}
	    },
	    'III' => 2
	    );


print_hash(\%hash);

sub print_hash {

    my($href) = @_;

    foreach my $key (keys %$href) {
	if (ref($$href{$key}) eq 'HASH') {
	    my $href2 = $$href{$key};
	    print_hash($href2);
	} 
	else {
	    print "$key => $$href{$key}\n";
	}
    }
}