import datetime
class Room:
    def __init__(self, room_number, room_type, rate, availability=True):
        self.room_number = room_number
        self.room_type = room_type
        self.rate = rate
        self.availability = availability

class Reservation:
    def __init__(self, room, start_date, end_date):
        self.room = room
        self.start_date = start_date
        self.end_date = end_date
        self.total_cost = self.calculate_tatal_cost()

    def calculate_total_cost(self):
        days = (self.end_date - self.start_date).days
        return days * self.room.rate

class Hotel:
    def __init__(self, name):
        self.name = name
        self.rooms = []
        self.reservations = []

    def add_room(self, room):
        self.rooms.append(room)

    def check_availability(self, start_date, end_date):
        available_rooms = [r for r in self.rooms if r.availability and
                          not any((start_date <= res.start_date <= end_date or start_date <= res.end_date <= end_date)
                                  for res in self.reservations if res.room == r)]
        return available_rooms