22. The Lobster General has a cannon. After the 1st firing, it takes 1 minute before the 2nd firing, after the 2nd firing, it takes 2 minutes before the 3rd firing... The interval time after each firing is 1 minute more than the previous one. The Lobster General can fire the cannon $\qquad$ times at most in 11 minutes.
(Not counting the time for firing the cannon)
$5$