99. In a certain martial arts conference, there are nine levels of experts participating, ranked from highest to lowest as Ranger, Musketeer, Knight, Swordsman, Samurai, Archer, Mage, Hunter, and Priest. For fairness, the grouping rules for the competition are: two or three people form a group. If two people form a group, their levels must be the same; if three people form a group, these three experts must either be of the same level or from three consecutive levels, one from each. There are 13 people, including three Rangers and three Priests, with one person from each of the other seven categories. If one more person joins, all these people will be divided into five groups for the competition. In this case, the level of the new person joining can have $\qquad$ choices.
Answer: 9