Laravel 5.3 validation to check whether a input value is same as given value in rule

I am using a date range and total number of days between that as another field. I wish to validate the number of days field with the duration between the date range using Laravel 5.3 validation. For example, If i give

$request->input('start_date') ="2016-12-28";
$request->input('end_date') = "2016-12-30";
$request->input('total_days') = "2";

then there should be an error saying that "the total number of days mismatch with the duration"

Please help me in achieving this.

via Chebli Mohamed