The cycle calendar

You will write a small calendar of the menstrual cycle. It gives the day of ovulation, the phase of any day, and the number of days in each phase.

The idea. Ovulation is $14$ days before the next menstruation. Days $1$ to $5$ are the menstrual phase. The days between day $5$ and ovulation are the follicular phase. The days after ovulation are the luteal phase.

Your tasks.

1. Finish ovulation_day. It gives the day of ovulation for a cycle of length days.
2. Finish phase. It gives "menstrual", "follicular", "ovulation" or "luteal" for a day.
3. Finish phase_lengths. It gives a dictionary with the number of days in each phase.