$ perl hashmath.pl 
@times has 4 elements
$VAR1 = [
          '2014-06-01 00:00:00',
          '2014-06-02 00:00:00',
          '2014-06-03 00:00:00',
          '2014-06-04 00:00:00'
        ];
Subtracting 2014-06-01 00:00:00 from 2014-06-02 00:00:00
Subtracting 2014-06-01 00:00:00 from 2014-06-03 00:00:00
Subtracting 2014-06-01 00:00:00 from 2014-06-04 00:00:00
@times has 3 elements
$VAR1 = [
          '2014-06-02 00:00:00',
          '2014-06-03 00:00:00',
          '2014-06-04 00:00:00'
        ];
Subtracting 2014-06-02 00:00:00 from 2014-06-03 00:00:00
Subtracting 2014-06-02 00:00:00 from 2014-06-04 00:00:00
@times has 2 elements
$VAR1 = [
          '2014-06-03 00:00:00',
          '2014-06-04 00:00:00'
        ];
Subtracting 2014-06-03 00:00:00 from 2014-06-04 00:00:00
$