#!/usr/bin/perl
use strict;
use warnings;
use Time::Local;

sub str2time{
	   my $in = shift;
	   my ($hour, $min, $sec) = split (/:/, $in);
	   my ($mday,$mon,$year) = (localtime(time))[3,4,5];
	   my $retn;
   			eval {      $retn = timelocal($sec,$min,$hour,$mday,$mon,$year);   };
   	 return $retn;
  }	   
	
print "Please enter the first time in HH:MM:SS format: ";
my $intime = <STDIN>;
chomp $intime;
my $time1 = str2time($intime);
die "Invalid time: $intime\n" if !defined $time1;	   

print "Please enter the 2nd   time in HH:MM:SS format: ";
$intime = <STDIN>;
chomp $intime;
my $time2 = str2time($intime);
die "Invalid time: $intime\n" if !defined $time1;

my $diff;
if ( $time1 > $time2 ) {    $diff = $time1 - $time2}
else {    $diff = $time2 - $time1}

my $mins  = int($diff / 60);
my $hours = int($mins / 60);
$mins     = $mins - ($hours * 60);
my $secs  = $diff - ($mins  * 60);
printf "Difference: %02d:%02d:%02d\n", $hours,$mins,$secs;