INTEREST INCOME, NET: (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019
INTEREST INCOME, NET:
Interest income on savings	$ 137	$ 70
Interest income on notes	6	7
Interest income on deferred purchase price	191
Interest expense		(25)
Interest income, net	$ 334	$ 52