text: ### Part 1
  def day_of_the_week():
      import datetime
      now = datetime.datetime.now()
      day = now.weekday()
      days = dict(zip([i for i in range(7)],
                      ['Monday', 'Tuesday', 'Wednesday',
                       'Thursday', 'Friday', 'Saturday',
                       'Sunday']))
      return days[day]
  
  print(day_of_the_week())
  
  ### Part 2
  
  def countdown_birhtday():
      from datetime import date, datetime
      bd = input('Please enter your birthday (YYYY-MM-DD):')
      bd_year, bd_month, bd_day = (int(i) for i in bd.split('-'))
      today = datetime.today()
      diff = datetime(today.year, bd_month, bd_day) - today
      if diff.days < 0 : return (-1) * diff.days
      else: return diff.days
  
  print(countdown_birhtday())
  
  
  ### Part 3
  
  def find_double_day():
      from datetime import datetime
      b1 = input('Please enter the first birthday (YYYY-MM-DD):')
      b2 = input('Please enter the second birhtday (YYYY-MM-DD):')
      b1_year, b1_month, b1_day = (int(i) for i in b1.split('-'))
      b2_year, b2_month, b2_day = (int(i) for i in b2.split('-'))
      b1 = datetime(b1_year, b1_month, b1_day)
      b2 = datetime(b2_year, b2_month, b2_day)
      diff = b1 - b2
      if diff.days < 0:
          b1 + (-1)*diff
          return b1
      else: return b1 + diff
  
  print(find_double_day())
  
  ### Part 4
  
  def find_double_day(n):
      from datetime import datetime
      b1 = input('Please enter the first birthday (YYYY-MM-DD):')
      b2 = input('Please enter the second birhtday (YYYY-MM-DD):')
      b1_year, b1_month, b1_day = (int(i) for i in b1.split('-'))
      b2_year, b2_month, b2_day = (int(i) for i in b2.split('-'))
      b1 = datetime(b1_year, b1_month, b1_day)
      b2 = datetime(b2_year, b2_month, b2_day)
      diff = b1 - b2
      if diff.days < 0:
          b1 + (-1)*(n-1)*diff
          return b1
      else: return b1 + (n-1)*diff
  
  print(find_double_day(5))
  