#!/usr/bin/perl

use strict;

my %students = ();

$students{456234567} = {
  name => 'Bob Smith',
  major => 'Engineering',
  level => 'Graduate',
  classes => {
    COMP8769 => {
      teacher => 'Dr.Smith',
      time => 'MWF 10:00',
      grade => 'A' },
    COMP7960 => {
      teacher => 'Dr.Smith',
      time => 'MWF 11:00',
      grade => 'B' },
    COMP7100 => {
      teacher => 'Dr. Rose',
      time => 'MWF 1:00',
      grade => 'B' },
    COMP7600 => {
      teacher => 'Dr. Gillian',
      time => 'MWF 9:00',
      grade => 'A' }}};

$students{852234567} = {
  name => 'Ivan Milla',
  major => 'Business',
  level => 'Undergrad',
  classes => {
    BUS4000 => {
      teacher => 'Dr. Rossa',
      time => 'M 2:00',
      grade => 'C' }}};

$students{123234567} = {
  name => 'Sergio Veara',
  major => 'Arts',
  level => 'Graduate' };

$students{987234567} = {
  name => 'Richard Thompson',
  major => 'Economics',
  level => 'Undergrad',
  classes => {
    ECON6900 => {
      teacher => 'Dr. Jones',
      time => 'W 9:00',
      grade => 'A' }}};

$students{963434567} = {
  name => 'Patrick Klivert',
  major => 'Economics',
  level => 'Graduate' };

$students{789234567} = {
  name => 'Janfranco Vialli',
  major => 'Engineering',
  level => 'Graduate',
  classes => {
    BUS4000 => {
      teacher => 'Dr. Rossa',
      time => 'M 2:00',
      grade => 'A' }}};

# this will display the values of the hash

foreach my $key (sort keys %students) {
  print "\n$key\n";
  foreach my $kee (keys %{ $students{$key} }) {
    print "  $kee : ";

    if (ref($students{$key}{$kee}) eq 'HASH') {
      foreach my $kei (keys %{ $students{$key}{$kee} }) {
        print "\n    $kei : ";   

        foreach my $kea (keys %{ $students{$key}{$kee}{$kei} }) {  
          print "\n      $kea : $students{$key}{$kee}{$kei}{$kea}";
        }
      }
    }
    else {
      print "$students{$key}{$kee}\n";  
    }
  }
}
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