input: Write a python function that calculates the number of available work days for an employee given a total number of days and a list of meeting periods. The function should return the number of days during which the employee has no meetings scheduled.
  
  from typing import List
  
  def available_days_without_meetings(total_days: int, meetings_schedule: List[List[int]]) -> int:
      """
      You are given a positive integer total_days representing the total number of days an employee has (starting from day 1). You are also given a 2D array meetings_schedule of size n where meetings_schedule[i] = [start_i, end_i] indicates the start and end days of meeting i (inclusive).
  
      Return the number of days when the employee is free for work without any meetings.
  
      Note:
      Meetings may overlap.
  
      Examples:
      >>> total_days = 10, meetings_schedule = [[5,7],[1,3],[9,10]]
      2
      >>> total_days = 5, meetings_schedule = [[2,4],[1,3]]
      1
  
      Constraints:
      1 <= total_days <= 10^9
      1 <= meetings_schedule.length <= 10^5
      meetings_schedule[i].length == 2
      1 <= meetings_schedule[i][0] <= meetings_schedule[i][1] <= total_days
      """
output: def available_days_without_meetings(total_days: int, meetings_schedule: List[List[int]]) -> int:
      busy_days = set()
      for start, end in meetings_schedule:
          for day in range(start, end + 1):
              busy_days.add(day)
      return total_days - len(busy_days)