check for an existing user laravel eloquent

$user = User::where('email', '=', Input::get('email'))->first();
if ($user === null) {
   // user doesn't exist
}

$users = User::where('email', '=', $request->input('email'))->first();
if ($users === null) {
  // User does not exist
} else {
  // User exits
}

if (User::where('email', '=', Input::get('email'))->exists()) {
   // user found
}