def weeks_elapsed(day1, day2):
    """ (int, int) -> int

    day1 and day2 are days in the same year. Return the number of full weeks
    that have elapsed between the two days.

    >>> weeks_elapsed(3, 20)
    2
    >>> weeks_elapsed(20, 3)
    2
    >>> weeks_elapsed(8, 5)

    >>> weeks_elapsed(40, 61)

    """
