input: Write a function to convert a given number of days into years, months, and days.
  assert convert_to_ymd(400) == (1, 1, 5)
  assert convert_to_ymd(365) == (1, 0, 0)
  assert convert_to_ymd(730) == (2, 0, 0)
  assert convert_to_ymd(800) == (2, 2, 10)
output: def convert_to_ymd(days):
      years = days // 365
      days %= 365
      months = days // 30
      days %= 30
      return (years, months, days)