Note 2 - Earnings Per Share - Schedule of Anti-dilutive Shares (Details) - shares	3 Months Ended		6 Months Ended
	Nov. 30, 2023	Nov. 30, 2022	Nov. 30, 2023	Nov. 30, 2022
Preferred stock convertible into common stock (in shares)	3,333,333	3,833,333
Preferred Stock Into Common Stock [Member]
Preferred stock convertible into common stock (in shares)	3,333,333	3,333,333	3,333,333	3,333,333
Warrants Exercisable Into Common Stock [Member]
Preferred stock convertible into common stock (in shares)	0	500,000