Note 5 - Stockholders' Equity (Deficit) - Schedule of Warrants (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Outstanding, warrants (in shares)	485,739	500,739
Outstanding, Warrants, Weighted average exercise price (in dollars per share)	$ 2.13	$ 3.63	$ 3.71
Outstanding, Weighted average remaining contractual life (years) (Year)	4 months 6 days	1 year 7 months 24 days	2 years 8 months 4 days
Exercised, warrants (in shares)	(309,252)	(15,000)
Outstanding, warrants (in shares)	176,487	485,739