SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Earnings per share (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings per share
Common stock underlying issued and outstanding stock options	8,194	26,604
Common stock issuable upon the conversion of convertible preferred shares
Diluted EPS calculated under the treasury stock method	8,194	26,604
Net Income	$ 429,384	$ 990,972
Preferred stock dividend requirements	(57,611)	(58,111)
Income applicable to common shareholders	$ 371,773	$ 932,861
Average common shares outstanding	29,937,159	29,937,159
Average common and common equivalent shares outstanding - assuming dilution	29,945,353	29,963,763
Basic earnings per share	$ 0.01	$ 0.03
Diluted earnings per share	$ 0.01	$ 0.03