Note 2 - Earning Per Share - Schedule of Basic and Diluted Earnings Per Share (Details) - USD ($)	3 Months Ended		9 Months Ended
	Feb. 29, 2024	Feb. 28, 2023	Feb. 29, 2024	Feb. 28, 2023
Net income attributable to common stockholders	$ 151,456	$ 3,562,996	$ 2,567,830	$ 4,471,124
Net income (loss) attributable to common stockholders	$ 151,456	$ 3,562,996	$ 2,567,830	$ 4,471,124
Basic (in shares)	28,279,701	28,279,701	28,279,701	28,279,701
Basic (in dollars per share)	$ 0.01	$ 0.13	$ 0.09	$ 0.16
Preferred Stock Dividends, Income Statement Impact	$ 0	$ 132,500	$ 0	$ 361,267
Net income allocated to common stockholders	$ 151,456	$ 3,695,496	$ 2,567,830	$ 4,832,391
Incremental shares from assumed conversion of options, warrants and preferred stock, as appropriate (in shares)	495,455	3,824,564	495,000	3,825,723
Weighted average common stock outstanding - diluted (in shares)	28,775,156	32,104,265	28,774,701	32,105,424
Diluted (in dollars per share)	$ 0.01	$ 0.12	$ 0.09	$ 0.15