#!/usr/bin/perl

use strict;
use Date::Calc qw /Delta_DHMS/;

my $total;
my $d;

open in, "log";
while($d = <in>) {
    $d =~ m/(\d+):(\d+):(\d+)\s+(\d+)\/(\d+)\/(\d+)/;
    my @d1 = (2000 + $6, $4, $5,  $1, $2, $3);

    $d = <in>;
    $d =~ m/(\d+):(\d+):(\d+)\s+(\d+)\/(\d+)\/(\d+)/;
    my @d2 = (2000 + $6, $4, $5,  $1, $2, $3);

    my ($days, $hours, $minutes, $seconds) = Delta_DHMS( @d1, @d2 );

    $total += ($days    * 86400
             + $hours   * 3600
             + $minutes * 60
             + $seconds
    );
}
close in;

print "Total seconds: $total\n";